Returning from the playground that afternoon, both of the twins' minds were on what they'd seen Uncle Paul and Aunt Alice doing in the den yesterday. Though they didn't say anything to each other about it, that's all the children could think about.

During dinner that evening, Jimmy kept glancing at his aunt and uncle, vividly recalling how exciting it had been to watch his big hard cock fucking into her pussy. The kid had been walking around with a hard- on since yesterday afternoon, and the feeling wouldn't go away.

As the evening slowly dragged along, Jimmy couldn't get his mind away from fucking, and as soon as he went to bed, the horny kid began excitedly beating his meat. He was almost on the verge of popping his nuts when the door opened and Amy tiptoed into the room. He realized it was only his sister, but he got a funny feeling in his cock when the light from the hall silhouetted her naked body through the thin material of her nightie.

"Are you awake?" she whispered, walking over and sitting down on the edge of his bed.

"Yeah," he grinned, turning on the bedside lamp. "I can't seem to get to sleep."

"Neither can I," giggled Amy. "I keep thinking about Uncle Paul and Aunt Alice."

"Me, too."

"Jimmy," she asked, her face slightly flushed with embarrassment, "did you really have a hard-on when you were rubbing the front of your pants yesterday?"

"Sure," he grinned.

"Was it as big as Uncle Paul's?"

"Shit, no."

"Do you have a hard-on now?" his sister excitedly asked.

"No," he answered honestly. He had quickly lost his erection when Amy had unexpectedly walked into the room.

"Jimmy." She hesitated. "Will you show me your prick?"

"Why?"

"Well," she giggled. "I remember seeing it when we were youger, but I'd like to see it now that you're big."