3 guys go for dinner, each buys a $10 steak. At the end of the meal, they collect $30 between the three of them to cover the cost of the meals and gives it to the waitress. She goes back to the cash register, where the overlooking manager says "Those dinners are discounted, you need to give them $5 back." So the waitress gets the five dollars, and returns to the table. Not knowing how to split $5 between the three of them, she gives 1 dollar to each of the three patrons, and kept two for herself.

Now if you do the math, together they paid $30, got $3 back meaning they only paid $27. The waitress kept $2. This totals $29. Where did the last dollar go?