When someone (preferably a woman) squats over your face and shits in your mouth. You then chew it until it is mushy or just generally chewed up and then regurgitate it back into their asshole.
You didnt create a big enough brown rocket for our three course meal
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.