"Bippity Bobbity Boo, Boo Radley is coming for you!"
"Bippity Boppity Boo, Donald Trump is gonna deport you!"
"Bippidy boppidy boo! Bill Cosby is coming for you!"
There is a ghost baseball game and one team loses because of one player so they start booing him!
Pete: Knock, knock...
Paul: Who's there?
Pete: Boo...
Paul: Boo who?
Pete: Don't cry, it was only a joke!
Paul: I'm going to cry! It was such a bad joke!!!
Knock, knock.
Who's there?
Boo.
Boo who?
Don't cry, it's just a joke!
Knock knock.
Boo.
No need to cry, it was only a joke. Yeh, I can't think of anything.
Booooooooooooo!
"BU" is the element of a surprise. Boo!