When you wake up in the morning and having an extremeley bad taste in your mouth. The taste is caused by smoking ciggeretes and or weed from the night before.
( guy wakes up )
guy 1- Eww dude, severe case of poo poo mouth!
guy 2- yeah i told you not hit that fatty before you crashed.
An insult which has evolved from shit-head.
Describes a man or woman receiving anal sex then performing fellatio on the feces covered member, thus getting feces in ones mouth.
Jill: Why do you call him a poo mouth?
Andy: Because he lets men have sex with him in the bum and then gives them a blowjob thus getting poo in his mouth. Hence, poo mouth.