Urinating backwards. Also an animal such as a raccoon that urinates backwards. From the Latin retro- (back) + mingent from mingere (to urinate).
"You have revealed yourself as a miserable, carping, retromingent vigilante, and I for one am sick of wasting my time communicating with you" (Benjamin C. Bradlee, Editor, The Washington Post).
some fucking ro-gangster that acts like they have a old account on the game Retroblox or Retrostudio in Roblox
Guy 1 : you see that fucko over there?
Guy 2 : yeah, why?
Guy 1 : he acts like a fucking retrobanger, cause hes an actual ro-gangster outside of this game
Retrobanger : AY FUCK YOU CUZ!! I LIVE IN THE HOOD AND ILL POP YO ASS!