A clever saying from the book "Hocus Pocus" by Kurt Vonnegut that he uses as a term for the end of the Vietnam War.

This saying now can be said to reprisent the ending of something that you'd rather not say, such as a relationship or a friendship.
Girl 1: "Why don't you and Nick talk anymore?"
Girl 2: "Well, after the excrement hit the air-conditioning, he just turned into a complete asshole and stopped talking to me."
by super_juicebox October 24, 2006
A phrase used to signal when some inevitable bad thing has happened.
Everyone involved usually gets punished or ill effects.
A different version of "when the shit hits the fan"
Phil called the bouncer an idiot. After the excrement hit the air-conditioning and now Phil and all his mates are banned from the club
by TaintedDeity May 13, 2008