Three Men at a Hotel
Hercules, Santa Claus and Prince Charming enter a hotel and pay the confused manager $30 for a room($10 for each man). Later, the manager realises he has overcharged them and gives $5 to the bellboy to return to the men. As the bellboy walks up the stairs of the surprisingly cheap hotel, he ponders that the $5 note won't easily divide by three between the men and definately doesn't wish to start some money fight between such important people. When he knocks on their door he ends up handing them just $3 in coins, keeping $2 on the sly.
The men have now paid $27 for the room and the bellboy has $2. Where is the final dollar?
Caution: Many people say "there is no missing dollar" - but unless you can explain why, without confusing yourself, your answer should be considered wrong.
This is a puzzle based off confusing people by putting them in a logically illegal situation and forcing them to try to make sense of it. Solving it requires backtracking to the logic error and rejecting it. Naturally, there is no missing dollar, so what is happening?
The men paid $27, of which the bellboy has $2 and the hotel manager has $25. 27 = 2 + 25.
You could try doing 27 + 2 = 29, but it produces a non-meaningful result. (What does that $29 represent?) You've added the same $2 twice over(which is wrong). If it is so important to add things to $30, then go with the sum of 25 + 2 + 3 = 30, representing the amount of money that each group of people now have.
The point of this problem is to confuse people - if your math isn't hot, you're probably still confused.
Those with active math usage, like accountants, won't even understand how this can be considered a puzzle.