Learned a cool word on Mecha-ike a few weeks ago – キレた. You can see the video for yourself here. Watch for a minute or so from the 6:30 mark.
Clearly it’s the past tense of the verb キレる. I’m not sure where it comes from (切る comes to mind) or why it’s half katakana half hiragana, but the meaning is totally clear from the video – it means that someone has just fuggin lost it, gone ballistic, bonkers, completely mad, etc. We had a case of that in the office this week, and immediately this phrase came to mind.
I made a sort of visual mnemonic to help you all remember the meaning:
That is the definitive キレた moment in American cinema.