Scissors

"Rock, paper, scissors, shoot!"

You both hold out scissors. He looks at your face in sorrow, silent. You figure this is a good opportunity to get even more.

"Oh well stepbro, I did get here first you know...."

"Please Lucy, I really need to go, I don't have time for this."

He'll definitely accept any terms now. You can't help but smile at him.

"Fiiine.. I guess we can play again. But this time, if I win, I'm going to do a little more than kick you."

He doesn't know what he's accepting, but he has to. "Whatever." He says, trying not to think about what might happen.

You don't waste any time. "Rock, paper, scissors, shoot!"