A person who says foul things all the time. ie. as if shit were coming out of the person's mouth
Tell that "shit mouth" to stop saying bad things about me.
by Brian March 12, 2005
Happy St. Patties Day!
Really, really bad breath. Breath that smells like a small animal has died and decomposed in someone's mouth. The type of breath that makes you gag when someone with it is standing within 3 feet of you.
Gary has chronic shitmouth, I nearly vomited when he was talking to me.

New Colgate Total toothpaste fights the leading cause of shitmouth.
by WeezleBlondini March 28, 2014
Happy St. Patties Day!
a person who has diaherrea of the mouth. someone who talks so much, you want to punch them.
stop shitmouth!!

by djs October 03, 2003
Happy St. Patties Day!
When you have shit in your mouth, from anyone/thing.
"hey, this shit tastes good!"
by Matthew Penfold September 22, 2003
Happy St. Patties Day!
A Shitmouth is a liar, a BAD liar.
Someone who will maintain their lie was true, even when they're trumped by evidence.
"I know you cheated on me, the tramp told me herself! You're nothing but a Shitmouth!!"

"Dude you can't believe anything he says, he's always been a Shitmouth"
by Grumple June 30, 2009
Happy St. Patties Day!