Replicating the sound of a gunshot to indicate vigorous approval; usually uttered in rapid succession with an accompanying thrusting of the hand in the air.
BUP is being true friends with a person otherwise known as besties under pressure a friend or best friend might leave you but your BUP willalways be there and never leave
"You're my BUP Simone" "aw thanks so much Zac your my BUP too, I love you BUP"