The sound a crowd makes when upset. To make such a noise is to boo.

Can be told from the noise made when scaring someone (boo!) by its 3(+) O's.
DiggityMan: And that, dear friends, is why we must collect the garbage twice (two times) each week.

Trash Collection Committee: Booo!
by Diggity Monkeez April 19, 2005
Pornography term similar to the 'Money Shot'. At the end of a porno film where the male climaxes, usually an aimed effort in the facial area of the co-star.
"Hey champ! I was watching this sick gonzo porn last night and you should have seen the Booos!"

"I meet this chick at the club, took her home and.... BOOOS!"
by Drew Scott February 10, 2006
A comeback people use when nothing comes to mind after the initial insult to themselves from another person, likely to have more people join in on the "boo" to more down the insulter.
Guy 1: You wanna fight bro?
Guy 2: You dont wanna fight me il knock you into next week...
Guy 1: Booooooo

People watching/friends of Guy 1: Booooooo
by cford_fluffers May 12, 2015
ghost, person jumps out and shouts booo

when a person get happy slapped round the chin chinolaeveryone else shouts booo. as in shame u smelly poo face chin
booo you just got happy slapped, u poo face chin
by MrW February 2, 2005
A scarier version of booo (or a cheep word in scrabble)
by ScrabbleThot.com October 24, 2020
The insult or expletive of last resort when you have used everything else in your exasperation, fury and or despair. First heard by the fans of a hopeless football team who were sick of seeing their side being so useless.
Aberdeen Supporter at game: C'Mon ye useless cunts! ye are shite! Ye're fucking useless...Ye hopeless bastards...BOOO! FUCKING BOOOOO!

Irish Person: This government is fucking useless! Fianna Fáil have marched us all into poverty! Our fucking country has gone to shit under the useless cunts! BOOOOO!! FUCKING FUCKING FUCKING BOOOO!!!!
by ShamboMaximus November 22, 2010