you're doing what??

The kids were getting rowdy. Easy answer. We send them outside. Addie bolted into the backyard. Miles had to get some clothes on. (See last post.) Jason and I were in the kitchen. Miles ran upstairs to find shorts and a shirt. Here is the conversation:

Addie: Dad!! Tell Miles we're going to play the butt game!
Jason: Okay. [relays the message]
Miles: Tell Addie I'm going to be the poop!
Jason: Okay. [again, relays the message, not knowing at all what the heck this game is.]
Both kids run outside. I start cleaning up the cake stuff and casually look out the window at the kids amidst wild laughter. I see Addie in the play tent, and Miles behind her half in the tent, half out. They are about to go down the slide.
Me: Noooooooo!!
They freeze and the butt game is now banned.