Trophy-- noun: Anything taken in war, or in hunting, etc.; a spoil, prize: esp. if kept or displayed as a memorial. Also fig.
Bang-- verb: To copulate (with), to have sexual intercourse (with). slang.
Trophy-bang--: either noun or verb: To copulate with another individual for the express purpose of a bragging rights
Jeremy could have trophy-banged the lead guitar player's girl but preferred to remain loyal to his sweet girl.