Derived from a transposition of shit hits the fan. Used in replace of shit hits the fan to try to regain some of the comic style and originality that the phrase used to have by making the listener think for a second. Also makes the phrase okay in front of the kids.
Black guy overhearing the conversation also on a cellphone:" Yo man, I just heard this white bitch talkin bout "the fit hit the shan" and shit."
Black guy on the line: "You sure she didn't say "the shit hit the fan"?
Black guy1: "Nah man, that bitch straight out said "the fit hits the shan!"