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ガチギレ gachi gire
Not annoyed. Actually furious.
What does gachi gire mean?
ガチ (for real) welded onto キレる (to snap). Everyday irritation has levels, and this is the top one — usually the quiet-voice kind.
Example
無断で使われて、さすがにガチギレした。
Someone used it without asking, and yeah, I properly lost it.
Vibe
Who you can say this to, and how it lands.
Friends only Casual. Natural with friends, out of place at work or with strangers.
The story behind gachi gire
Both halves have a history. ガチ comes from ガチンコ, sumo world jargon for a bout fought for real rather than arranged, and it spread nationally through television before settling in as the standard prefix for no exaggeration. キレる, meanwhile, was everywhere in 1990s news coverage about people losing control.
Put them together and you get an inflation marker. So many small annoyances were being described as キレた that the word stopped meaning much, and ガチ was drafted in to restore the weight. The irony is that real ガチギレ is usually quiet: no shouting, no scene, just a friend going very polite and very short with their sentences.