A crap so bad it is said to stain the toilet bowl. This can be due to the size of the crap, or, alternatively, because of the painful feeling incurred before or during said crap, probably caused by the food ingested to create the aforementioned crap.
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.