The "griznatch" is the area just left and right of a males penis on the upper thigh area. Prone to heavy sweating and very painful muscle aches which will make the man walk awkwardly for days.
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.