Hooray for shared cultural context

At dinner, we're contemplating who's going to put tip money on the table.

Me: I forgot to get cash.
Pygment: (pulls out money) I didn't.
Me: *filches a 20*
Pygment: Hey! You took my money!
Me: Where do you think that money came from in the first place?
Pygment: The bank!
Me: How can you still have money? You're out of checks!

(context: earlier that day we'd discovered that we were in fact out of checks - Pygment had to order more.)