A UBG (Unwanted Birthday Gun) is what an American man in the West or South receives on his birthday if he is not interested in hunting or target shooting.
I could easily protect us from a zombieattackdue to my supply of UBGs.
"A Ubg mf" (An Untitled Boxing Game Motherfucker) meaning;
A person who crossdresses, is acting like the opposite gender, might be homosexual or is just a salty/unmeaningful person
"You don't play fair, man! You always just do the same move on me!" - Person 1
"Oh, you a ubg mf." - Person 2
A person who sends writes letters, post cards, greeting cards, textmessages etc. to him-/her-self, and pretends that the correspondence is from someone else.
Mr. Bean often sent a birthday card to himself. What an ubgook!