2 situations that made me mad recently:
... you are 1 turn from EM Chaos Lord with an old timebow, and he plays Explosion on your Eternity, and you deck out.
... you try quickly play tower and press space. The game dont get the play tower command, but get the end turn, and when you try again, you just discard your single tower. Oh, and you are against a Pest deck. And had 4 consecutive wins in Bronze League.