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.