Hit The Fan Meaning

(idiomatic, intransitive) To have a dramatic, usually negative, effect.

Example:   They were just clowning around, when suddenly it all hit the fan.
  Then the shit really hit the fan.
2004 December 2, Neal Cavuto, “Interview With Jeff Flake”:
  Let me ask you, Congressman, the case of a lot of these corporate scandals, I followed enough of them to know how -- how it works out. Once everything starts hitting the fan, the CEO, the chairman or maybe a large share of the board of directors simply leaves, resigns