When you expect to fuck someone in the ass, but in a surprise turn of events, you get fucked in the ass instead.
I thought I was going to be the one in control last night, but he pulled a total Reverse Nigerian Prince on me, and I'm the one who can't sit down today.
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.