An adjective (with emphasis on the second 'boo') used to describe anything and everything that sucks, whether it be a bad situation, something disappointing, etc, but isn't extremely terrible. Usually placed at the beginning or end of a sentence.
Jesse, I changed the date for my party just for you and now you can't come? That's boo boo.
Ahh, boo boo! I forgot to write my paper!!!
Seriously? He gave us homework on the first day of school?! Boo boo.
Ahh, boo boo! I forgot to write my paper!!!
Seriously? He gave us homework on the first day of school?! Boo boo.
by VonKeiss August 24, 2008