Its when you tell us too much information that we don't need to know. Like the fact that I haven't washed my dick for a week and the smegma is starting to get stuck and ferment.
The reaction used to be called "Powerlevel" as a reference to Dragon Ball. Like the others said, it's when you reveal too much about your private life (Reveal your powerlevel).
its a seatbelt advising the poster to buckle up bc they're in for a wild ride. it's also a way for BP to dogpile on anything outside their limited cat lady experience and/or posted by a man