When one farts into a taco, or anything else edible at tacobell. Usually done if a customer is an ass or is really picky. A mexican stinky salad can also be done anywhere in mexico too.
Yo! Jose...my hombra, that customer was an ass. Imma make him a special sandwich... A mexican stinky sandwich.
A trip to a grocery store, convenience store, or gas station for the sole purpose of buying an excessive amount of junk food and sugary drinks, usually with friends. A chud run often happens late at night and ends with everyone involved hating themselves afterwards.