Busting in your own cheeks normally doing so by rubbing the cock and balls in between the cheeks of the anus, doing so resulting in busting on your own buns.
Person A: “dude how’d your buns get so sticky I can’t even fit it in?”
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.