Derek was in his room, reading his new playboy. It had just come in the mail today. He was especially interested in the photos of his favorite actress, Natalie Portman. With every flip of the page, his cock was getting harder and harder. Finally, he couldn't wait any longer, so he took off his shorts and boxers, and stated jerking off. Just as he started, his little sister Marty burst through the door. She said in shock, "Derek, what are you doing"? Derek was completely embarrassed to be caught by his baby sister. But then he thought, she's not a baby anymore. He was 25 and she was 14, maybe they could have some fun. He said, "Marty, have you started sex ed in school yet"? "Ya,we started 2 weeks ago. Why?" "Have they told you what a blow job is?" "Ya, it's when you suck on a guys penis...why?" Marty's thoughts went instantly to Derek's cock and she was surprised how OK she was about what she was thinking about. "Would you like one Derek?" "Sure," he replied, a bit surprised at how willingly she played along. She goy onto his bed and lowered her head between his legs. This was the first blow job she had ever given and she hoped she was doing OK. She put the tip of Derek's cock in her mouth and started bobbing up and down his cock. His cock was 8" long and she was able to fit the whole thing I her mouth. As she sucked his cock, derek was panting and moaning. His moaning made Marty feel all tingly in her private spot and she also felt her undies getting wet. Derek pulled his cock out of her mouth and then asked her, "Do you know what eating out is"? "No, what is it?" asked Marty. "It's when a boy sucks on your vagina and I've been told it feels really good." "Well can we try it?" asked Marty, "It sounds fun". With out another word, Derek lifted Marty's dress and pulled down her panties. What he saw was truly beautiful. He say a pussy that had never been touched. It was soaking wet and perfectly tight. He lowered his head between her legs and started licking. He parted her lips with his hands and stuck his tongue inside. With this, Marty let out a gasp. She had never felt this way before. Derek started exploring and Marty was moaning in pleasure. Sensing that she wanted to go further, Derek inserted a finger in her pussy. With this, Marty let out a huge gasp. She had never felt anything like it. Derek thrust his finger in and out of Marty's pussy while his thumb rubbed circles on her clit. Marty felt a wave of pleasure wash over her and she expelled some kind of liquid from her vagina. "Derek," Marty said worriedly, "What just happened"? "You just had your first orgasm, and you cummed! Now, do you want to feel what real sex is like?" "Yes please!" "OK," said Derek in anticipation of Marty's tight pussy said, "I want you to sit down on my penis and as you sit down, I'm gonna rub your clit. The first time I go in, it might hurt. Hopefully, the pleasure from me rubbing your clit will cover up the pain. After that, it's all pleasure. OK, ready?" Without responding, Marty lowered herself down onto Derek's huge cock as he rubbed furiously at her clit. She winced slightly as he popped her cherry, but soon let out a moan of pleasure as he started thrusting in and out of her tight pussy. The pressure on his cock was so much that he cummed inside Marty. This caused Marty to cum all over Derek's cock. He pulled out of her pussy and cum started dripping out of her pussy. They both collapsed on bed and drifted into dreams of each other.