"I have a headache. Go without me."
"No, come down to the pool with us. Francis invented a new game. It's amazing."
"I don't know. What game?"
"We take ten Nerf balls. They're foam and full of air, so they float. And you make a triangle out of them, floating in the middle of the pool."
"Ugh, and Francis gets drunk and jumps on them?"
"No, it's way more measured. Everyone takes turns aiming the pool skimmer and knocking an eleventh ball at the triangle of ten. They scatter and bob all over the pool, usually towards the filters."
"So, it's like billiards? I like billiards."
"Exactly like billiards. You get a point for every time one goes into the filter. It's really fun to see if you can aim with the way the water sloshes around. Kind of zen. I bet you'd be good at it."
"I might try it. What's it called?"
"Oh, Pool Ball."