turnsies
When you're playing a video game and you reach a level that is too hard, so you have someone else beat it for you and they get into it so much, to the point where they won't give you the controller back, and you have to remind them that you're taking turns by saying "turnsies."
After Joe wouldn't give me the controller back from beating the hardest level in the game, I had to remind him we were taking turns by saying turnsies .