Gotcha is a term that is often used in sports. It is usually used to describe a moment when someone managed to catch someone else by surprise.
He got the gotcha when he caught the ball at the last second.
She got the gotcha when she caught him in the lie.
noun
A potential problem or source of trouble.
noun
An instance of publicly tricking someone or exposing them to ridicule, especially by means of an elaborate deception.
noun
An instance of accomplishing a tricky idea or overcoming a difficult obstacle.
noun
A feature of a system or a program that works in the way it is documented but is counter-intuitive and almost invites mistake or non-function.