Anything unpleasant or contrary to what you want. Or, for your literal types, a taco filled with mud. Not yummy.

It can a euphamism to take the place of regular profanity shit damn fuck asshole
Man, I went out with this girl and she got drunk and blew chunks all over my pimpin' Aston Martin. It was a real mud taco.

They told me it was gonna be a good time, but it was really just a mud taco.

The world is filled with mud tacos, but you don't have to eat them.
by Zodiacdial November 3, 2006
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Noun. A male's rectum, usually after engaging in vigorous anal sex, that is hardly functional or useful for anything other then more anal sex.
Jake has been sleeping around with many men, and now his ass is a straight up mud taco. Damn.
by BODYMASSAGEMACHINE July 20, 2009
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A womans genitals after they have been penetrated by a penis that had just engaged in anal sex.
"Sloppy seconds aren't bad...but, I aint eatin' no mud taco!!!"
by tacock January 20, 2010
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