A problem just got worse, or a problematicinformation just went public.
When somthing that was supposed to stey a secret became known to the worse people, or a problem you dreaded just manifested
A: John sent the email to his boss by mistake...
B: The Shit just hit the fan
A: The software update included the virus, it was sent to all the clients by now
B: The shit just hit the fan
When discovery of an inopportune incident, usually pertinent to personal misconduct, indiscretion, dereliction or impropriety is made, that provokes outrage toward and/or has seriously negative consequences for the perpetrator(s).