1. the act or action of taking a shit or the shit itself. see also: dookie, poo poo (exact variation), shizat, #2, or just plain shit.
2. a general derogatory statement for a mistake or a bad action (more often used in the shorten version a "boo")
1. I gotta take a boo boo. That apple pie smells like stright boo boo! that damned cat boo booed on the carpet again!
2. Man that football play was straight boo boo!