On a 10+, you find Madison alone and ready

You walk across the hall to Madison's room. You hear her singing lightly inside. The hallway has a set of wet footprints coming from the bathroom to her door. She must have had a shower recently.

You open the door and close it behind you.

Madison has a towel wrapped around her body, holding it in place with her fingers. She turns at the door and squawks. "Tom! What are you doing here!"

You're really horny and it's affecting your thinking process. "I was looking for you, because I wanted to show you this!" you say as you drop your shorts to show off your cock. Perhaps coming right out wasn't a good plan.

Madison's eyes get really big when she sees your thick cock pointing rigidly at her. Her mouth drops open and her hand slips, letting the towel drop to the floor. Now it's your turn to gape at your sister's tight body. She's well-toned with a flat belly, narrow hips, and long legs. Her perky B-cup tits have fat hard nipples capping them.

As if in a trance, she walks over and kneels at your feet, unable to resist your member. You moan when she touches it with her tiny hands.