Never Say Never
I've got a bet on with Andrew that a particular piece of our code will never get into an infinite loop. The code is intended to generate a unique random string of characters. The only way the loop can happen is if it randomly chooses a preexisting value every time. This seems relatively unlikely, since there are 14776336 possible values. The record of our wager is on the office wall, right below the National Pen Company advertisement. (I'll have to tell you about that one sometime.)
Of course, neither of us will ever win: there's a never on both sides of the equation.