Bart Simpson woke up again at six. He stayed up all night watching "Late Night with McBain" and he didn't want to go to school. When he walked downstairs, he noticed a bulge in his pants. He had had these before, but never in the morning, only when he watched those shows on Fox. He arranged his green pajamas so that they covered him adequately, and went downstairs to fake to his mom. When he got downstairs, he saw his father running around because he was yet again late for work. He had just enough time to grab the last donut *Damn* and run out the door. Lisa made her way down, in her ugly blue pajamas. She was happy to be awake, because she always got good grades, and going to school was something she looked forward too. "Owww" Said Bart "What's the matter honey?" Marge asked, her concern obvious. "Ow, my ovaries" Bart groaned. "Well, maybe you should stay home today sweetie" Marge replied "No....must.....get....to....school" Bart intentionally gasped "What, do you have another history test, bart?" Lisa provoked "Lisa, give your sick brother a break. Bart, I order you to go to bed and rest" Marge commanded. Bart walked back up to his room *suckers*. As he made his way back up, he noticed his penis was still erect. He decided to watch some tv, to try to get his mind off of it. He changed around a few channels, watching the spanish fly guy get beaten *hahaha* and some stupid soap operas. * boring* When he switched to the soap opera, he noticed his penis began to feel great. He was so young he didn't know what to do, so he just pulled downhis pajama bottoms, to feel his penis. When he grabbed at his penis, he began to feel incredible feelings like he had never had down there. Suddenly, he heard his mother enter the room. "Bart, can I get you some food for my sick little guy?" His mother said. "Sure mom, I'd like some pancakes, some bacon, a couple toasts, some juice.." Bart was cut off by Maggie crying in the next room. "Oh, one minute, I have to get that. Would you come in and help me?" "Fine, if it helps me get food quicker." Bart groaned. Bart followed his mother into the room and helped as she changed Maggie's diaper. She then took her right breast out of her green dress and started feeding Maggie. As bart watched this he instantly became aroused, and he began to stroke his penis like he had in his room, to make it feel better. He was being as quiet as he could so he didn't disturb his mom. Maggie greedily sucked at her mother's breast, and as she did Marge's nipples began to become erect and sore. Maggie switched breasts after one was emptied out, and continued the same treatment there, and when she was switching a couple drops of the sweet white liquir dropped off her erect nipple and onto the floor, which the dog drank instantly. After a couple of minutes, much to his dismay bart climaxed. He panicked and ran to the bathroom. *oh man, i wet my pants, I can't believe it* He snuck back to his room and got some clean pajamas. On his way back, he noticed that his pajamas were sticking to his crotch, which was chaffing it. He made his way quicker on tiptoes so Marge wouldn't find him. He jumped into the shower, and he tried to get things rationally in his mind. *Ok Bart, you just wet your pants, you were sick, and mom was...oh no, not again* He thought as hispenis grew again. *come on Bart focus* "Honey, are you in the shower?" He heard his mother outside. *Shit* "Umm... yeah mom, I just want to get some of the germs off of me" "Ok, when your done tell me and I'll get your some breakfast." Bart breathed a sigh of relief as his mother left. He looksed down and saw his penis was still erect. *What the hell* he though as he began to masturbate again, and this time he noticed that he wasn't peeing his pants, it was something else. He knew he couldn't ask his mom, but Lisa was smart, maybe she would know. He finished up his shower and he put on the clean clothes. He walked out and grabbed his breakfast, then went in his room and locked the door. He didn't want to be disturbed by his mother again, especially not if he was experimenting and trying to figure out what it was that was coming out of him when he was doing what he did. Six Hours Later..... Lisa came home with another A+ on her paper. Marge hugged her and gave her attention, then Lisa went back to her toom to do her homework. *Perfect* Bart thought as he walked into his sisters room. "Umm... Lisa, I have to ask you something." Bart said coyishly "What, do you have a girrrrl friend?" Lisa teased "No, no, it's something much more different than that." Bart said as he told Lisa the entire story. Lisa listened to it and took out a couple of of her anatomy and biology books. "Well, according to this, your penis becomes erect whenever you have sexual stimulae." Lisa said scientifically "Guh?" Bart replied dumbfounded "Whenever you see something sexual, your penis grows." Lisa replied "Can girls do that? I know they have a different body and all?" Bart asked. "Yea, they can. It's like that movie dad has" "What movie?" Bart said "I found this once when we were gone during the weekend. Check it out." Lisa puts the tape into the VCR, and sees two hot big breasted blond women having steamy wet oral sex. After less than 30 seconds of this, his penis is full grown again, and Lisa notices and is amazed by the size. "Bart, your peepee is big again." Lisa says blushing "Umm... it's called penis, right? Just call it that." "Ok, your penis is erect again Bart" "Yeah, I noticed. Have you ever seen a penis in real life before?" "No I haven't" she said nervously. She knew what was to come. "Would you like to?" Bart asked, he wanted relief and he couldn't do that while his sister was like that. Lisa meanwhile, was trying to choose. Sure, she knew incest was wrong from Reverand Lovejoy, but she still was a scientist, seeking knowledge. And besides, she could always call her parents out to get Bart off if he went too far, and she didn't want to regret not having done something she could have. "Ok Bart, but try anything funny" She said, and Bart pulled down his Pajamas. His Penis sprang forth, and she was surprised to see the yellow meat. She had only seen scientific pictures of penises in her books, and they were nothing the size of an erect penis. "Can I...touch it?" Lisa asked timidly "Sure Lis, I thought you'd never ask." She began to stroke it, and Bart shook at the feeling of another person going down there. "Oh, that feels good Lisa, keep doing that." Bart began saying. Lisa was grabbing him like the rope at gym class, and it was turning him on so much. He was breathing heavy as suddenly the porn changed from two lesbians to a short fat man and an older redheader woman. The woman was sucking on the man's cock, deep throating it. "Lisa, can you do that?" Bart asked innocently. He saw the man in the movie was enjoying it, and he didn't think he'd have another opportunity anytime soon. Besides, Lisa seemed to be almost having as much fun as he was. "Ewww Bart, that's gross" Lisa said, although on second thought.. "Come on sis, it'll be like eating a hot dog, just don't bite. I just showered today, so it's clean." Lisa thought for a moment, then decided she would try it, and if she didn't like it she could always stop or call mom. She moved her head down to her brother's hairless crotch, and saw the size of the penis. She was amazed at how big it was when she was right up and close to it. As she began to put his penis in her mouth, She noticed it didn't taste bad, and let it in a little more. This set off fireworks in Bart's brain, as the combination of the porn movie and his sister's soft warm mouth continually sucking was blowing his mind. Lisa continued for a couple more minutes, getting it a little bit deeper in her mouth before Bart knew he was going to come. He moaned to his sis "I'm gonna do it!" She didn't have a chance to wonder what before he shot his entire load inside of her mouth. She was suddenly surprised to have a mouthful of sweet and salty tasting semen. She tried swallowing it, but alot of it spread off of her face and onto her chin, covering her little face. This made Bart even hotter, to see his little sister covered from her mouth down in his sperm. To her surprise, she actually liked the taste of it. She kept it in her mouth a minute longer, until she had to swallow it, then she took her fingers across her pajamas and scooped up the remainging sperm. The room was dead quiet, because of the fact Bart was ashamed and afraid that he had cum in his sister's mouth, he didn't want Homer to kill him, and the fact Lisa was really liking it. Bart was the first to break the silence. "Um... Lis, I'm real sorry about that." Bart apologised "It's ok Bart. I actually kinda liked it" "Is there anyway I can make it up to you?" Bart tried to make a deal,he loved the feeling and wanted some more. He was also afraid and he wanted to insure himself against getting in trouble. "I don't think so" Lisa said, and as she tried to think of something, she didn't want to make Bart think she liked the taste of sperm, but she did want to go further. Then she saw on the porno the girl climax while under the man. An idea popped in her mind. "Bart, could you do what they are doing on the tape?" Bart's eyes did an Ace Ventura double take, and all he could do after his first blow job is nod sheepishly. "Ok, so how do we do this?" Bart asked. "Umm.. let's take our clothes off first I guess." Bart was already half naked, and he had the chance to watch Lisa undress. He hadn't noticed before, but his sister really had a beautiful body. Lisa first took off her shirt and Bart began to notice her breasts, not only how small they were, but also how nice her nipples looked. Then she took off her pants, and Bart could admire her ass, he thought she had the cutest bum. "Ok Bart, come over here, and put your penis into my vagina." Lisa took control of the reins, she had to try to get Bart to believe this was scientific, and that she knew what she was doing. Bart went to her, and slowly set his penis at the tip of her wet mound. She looked over at him and nodded, and he slowly began pushing his penis into her. He didn't want to hurt her, and the feeling was so good that he didn't want to go to fast and orgasm too quickly. After a couple of inches, he came upon an intrusion. *What the hell?* He pulled out a little because he thought he had gotten to the end of her vagina, but his penis wasn't even halfway in. "It's my cherry bart, you're going to have to pop it." Lisa said. "Won't it hurt?" bart asked, genuinely concerned. "Yeah, but I can take the pain. For science." That was all Bart needed, and in one fellow swoop he poped his sister's cherry. She cried out in pain, and bit her lip. She nodded again after a couple minutes, and Bart began pumping. "Lisa...can I try something?" Bart asked. "Sure....uhhh...Bart...." Lisa said inbetwen moans. Bart lowered his head onto his sister's nipples, and began slowly sucking on them like maggie had. "Don't worry Lis, I saw mom do this" he said as Lisa was going crazy, she was having her vagina pumped and her nipples sucked on greedily for the first time ever. Bart was confused, he noticed that Lisa wasn't having any milk like her mom. He began to gently bite on his sister's nipples, which made them get aroused, and was killing Lisa. The feelings in Lisa began to swell, and she was having the most intense sensations she'd ever had. Bart began pumping slowly at first, but as her pussy began to become more lubricated from the constant action and her own reaction to his sucking, he went quicker. She was moaningat his quickening strokes. "Ohh....yeah...do it bart...deeper, please, I beeeeeeeeeg you, ohhh uhhh....thats good...oh my nipples...they're on fire....suck em oh Bart come on, faster, deeper, please, oh" Lisa was close to an orgasm, and she was aware of it. She moaned as Bart began to fuck her as fast as he can, his penis going in and out a hundred miles an hour, and Lisa riding him like a pony. Bart pulled his head back right as she was right about to climax, and Bart pulled his penis out entirely then placed it back in all the way, this sent her to ecstacy. She shook uncontrolably for minutes as she experianced a mind blowing cataclysmic orgasm. Feeling this, Bart kept pumping furiously, the combination of all the sex and his sister's orgasm was making him ready to cum. "Ohhhh, uhh.... Bart, that.....was....amazing, but wait...ohh, uh, god it's so good, don't orgasm in me, I don't want to be pregnant. Come on, I'll take your penis in my mouth again." Lisa said. Bart really liked it, and he pulled out quickly. He didn't want to take any chances, and lisa wanted to see if she could deep throat his entire cock, and as soon as he was out, she did her best. The penis was well lubricated with her own juice, and she was able to get it in halfway before it stopped, but then she relaxed her jaw muscles to forced it down until it was three quarters inside. Bart was going nuts, and he yelled "I'm gonna orgasm!" Lisa knew what to do, she took his penis, and held the head in her mouth, licking the tip of his penis. She knew he was going to cum, and she wanted to taste it the second it came out. Unbeknownst to her however, this was making Bart even hotter, he was on cloud nine for minutes until he had finished his orgasm. Lisa got as much into her mouth as she could, the rest she took and smeared over her nipples, which were still on fire.They both dropped into a hot sweaty pile on her bed. "Bart...huff...let's do that again sometime" Lisa huffed before passing out. Lisa had to think today out before she went any further. "Sure Lis....huff..., see ya ....later" Bart got out of his mouth before he stumbled to get his clothes on. As he was getting his Pajamas on, he noticed his sister was still playing with her vagina. He waited a minute as he watch his sister get hot and wet again. His penis had gotten erect, and he was pumping it furiously to cum again before she was done. She looked up and saw Bart was still there masturbating, and she said "Shoot it on my vagina" as Bart came a small load on her pussy, but she was burning so much that just that was enough to send over the edge again.