The phenomenon where you cannot, no matter how hard you try, squeeze out one drop of piss, no matter how hard you have to go. Usually in a public facility.
Al came back from the bathroom and said "Holy frozen mixed vegetable cocks!, do i ever have cockstipation again"
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.