So Thursday night Koz Achmed and I are playing Trivia, and our bill comes to $30, for which we all chip in equally.
Afterwards the owner comes up to us and says, "You guys were so cool I want to give you a discount" and hands us back five one dollar bills.
We give the server two dollars and each take a dollar back.
"Wait a minute," says Koz, as we are getting up to leave. "With the dollar back that means we each paid 9 dollars, which is 27 dollars total. We tipped the server 2 dollars, which makes 29 dollars all together. Where did the extra dollar go?"
[answer in credits]