pejorative meant to capture judicial lexicon of "guilty" but in more social context, i.e. phrase used to deem another's attempt at being cool or heady as effectively not cool or heady.
Dude 1: I got so heady last night. I must have drank 10 michelob ultras and then bombed out to drive-by truckers 2nd studio album
Dude 2: Flops down Bro, hecka poser.