I'm losing control of myself. Karen thought dizzily. She stepped closer to the couch, her huge mammaries heaving under her sweater, now staring openly at her kid brother's big prick. Jimmy started to smile as he finally saw what his sister was looking at. His cock got even stiffer, jerking up and down as the blood throbbed through his meat.

"You… you sure have a big one, Jimmy," the horny sister observed breathlessly. "I… I guess I never thought you'd have such a big prick. You being so young and everything."

"Thanks," Jimmy smiled.

"It… it's really stiff, too. You… you were just about to shoot off when I interrupted you, weren't you?"

"Just like I said."

"Then your prick must be all full of jism, Jimmy. It really must hurt."

Acting on impulse, feeling too horny to have any control over her actions, Karen suddenly knelt in front of her little brother. Jimmy just smiled down at her, his big prick throbbing and oozing, by now realizing that he was about to get his prick sucked.

"Maybe… maybe I ought to help you out a little with your boner, Jimmy," Karen said breathlessly. "Seeing as how it's my fault you didn't get to cum."

Karen raised her hand, trembling with cock lust as she wrapped her fingers tightly around the pussy juice-slickened root of her brother's cock. Then the big-tittied sister started jacking the mammoth hard-on up and down, making Jimmy moan with pleasure, skillfully whipping her fist up and down his big prick.

"Oh, Sis!"

"Is this making your prick feel better, Jimmy? You like it when I rub your cock like this, don't you?"

"Shit, yes!"

"I… I can suck it for you too, Jimmy. I… I know most people think that's wrong. You're my little brother. But, I… I think I should do it for you, Jimmy. I almost gave you blue balls. The least I can do is suck your big boner for you, and suck out your hot cum. I… I guess I think that's right…"