(third-person singular simple present hits the fan, present participle hitting the fan, simple past and past participle hit the fan)
- (idiomatic, intransitive) To have a dramatic, usually negative, effect.
- They were just clowning around, when suddenly it all hit the fan.
- Then the shit really hit the fan.
- Use with other subjects than shit is probably intended to evoke the image without actually saying the taboo (in some contexts) word.
This expression is almost certainly from colloquial expressions involving shit hitting the fan.