Here's a relatively common situation:
We've just solved some tricky puzzles; found some secret treasures; fought hoards of monsters with skill and finesse. The heroes seem smart and strong and powerful. Finally, it's time to unlock the door to claim the big prize... but someone fumbles with the key and ends up throwing it at the wall instead of unlocking the door.
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In real life, I can only imagine that I'd have to be extremely frustrated about something to end up throwing my keys at my front door instead of unlocking it. I just think it's funny to imagine what might cause characters in the game to do some of the things that they do.