The taste in your mouth when you wake up if you neglect to brush your teeth the previous night/day. Usually occurs from a night of heavy alcohol consumption. It can also have the feel and density of overly-sweetened honey.
Drinker 1: Man I have this horrible taste in my mouth.

Drinker 2: Dude you drank a lot last night and just passed out on the couch. You've got cat shit in the mouth.
by ajgenard September 11, 2009
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phrase used the morning after a heavy night of drinking. it refers to the very nasty taste left in one's mouth as part of a hangover.
cory: hey craig, you got any pets?
craig: no. why?
cory: cause last night i passed out on your floor, and i think a cat shit in my mouth.
by Joe Sausage May 25, 2005
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From a Meg Ryan movie 'Promised Land' and referenced to in Stephen King's 'Dreamcatcher' by Jason Lee. Lee as Jim/Beaver: "In the movies, when people wake up together in the morning, they immediately start kissing, nuzzling and going at it, but what they never do is get up first, take a leak and brush their goddamn teeth, which I don't think I'm alone in feeling is pretty much necessary when you wake up." then he says something like 'like meg ryan in that movie promised land'
Pete Moore (Timothy Olyphant): "Promised Land? Never heard of it."
Jim "Beaver" Claredon (Jason Lee): "Meg Ryan and uh whats his name? Reefer Sutherland..."
The Guys: "Keefer!"
Beaver: "...from I don't know 1988 or something. So, Meg Ryan wakes up in the morning and says "Where's the cat?" and he says "What cat?" and she says "The cat that shit in my mouth."
Morning breath is worse if you pass out without brushing your teeth, after a night of drinking and onion pizza after the bar.
~waking up the 'morning after'
Bev: Where's the cat?
Danny: What cat?
Bev: The cat that shit in my mouth.
Since my example has to use the exact phrase 'a cat shit in my mouth' and i quoted the movie and don't want to change it, I'll make more examples
~Amy: Damn where's that cat?
Chris: What cat? I thought you only had dogs
Amy: I do, but I think a cat shit in my mouth this morning"
~"Oh snap, your breath is so rank a cat must of shit in your mouth"
by Amy F. August 14, 2006
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