When you jizz, shit, piss, yawn, sneeze, fart, burp, and throw up at the same time. Than you put it in a blender and shove into your girlfriend's vagina. If you don't have a girlfriend stick it up your ass.
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.