"Bieber Banging" is when a man buys tickets to a Justin Bieber concert to meet young girls. Since those girls can't have Justin Bieber, most likely because he hasn't hit puberty yet, they end up settling for the next best thing: the closest guy. Later the guy ends up banging the girl and never seeing her again, leaving the girl emotionally scared for the rest of her life. "Bieber Banging" may include but is not limited to: 5-6 years prison time for statutory rape, an STD, and/or a little sign in your front yard that tells kids not to go to your house for candy on Halloween.
Guy 1: Dude, I just got done "Bieber Banging" a girl in the back of my car! Do you think I could go to jail?
Guy 2: No way man, that chick was probably 17 1/2.