Strip tennis.

"Just a game coach." She says through a giggling smile.

"What kind of game?"

"If I score a point you take off an article of clothing. If you win a point, I take one off. Whoever is completely naked first loses, and has to do whatever the other person wants."

"I don't know..."

"Come on coach," she grabs your crotch and whispers in your ear, "Don't you wanna?"