This riddle has been presented in numerous variants. In all of them, the question and answer is basically the same. Here it is:
Imagine you are holding two [American denomination] coins in your hand. The two coins total 30 (thirty) cents.
What are the two coins....keeping in mind that ONE of them *ISN'T* a nickel?
A quarter and a nickel.
But didn't I just say that one of the coins wasn't a nickel?
But that doesn't mean that the OTHER coin can't be a nickel....
Why do people get so offended when they can't answer this question...which is.....nearly everyone I've asked it to?
It's a simple yet brilliant brain exercise in thinking in more than one direction and dimension.
Perhaps the reason people get offended by it is because it reveals their inability to think in more than one way...
Just some food for thought.