normally
used as a dismissive for a person's comments or an
idea that is unwelcome or unpleasant. sometimes
used after a look of disbelief.
1)Friend: "Girl what are you wearing? You look a
mess."
Friend 2: "Ooh! Buh bye!"
2)
Guy (joking): "You wanna mess
around?"
Guy 2: "Dude! Buh bye!"