When a person gets really stoned to a point that he can tell the exact time of the next time he has to shit.This person gets the perfect understanding of when he has to take a shit.
Nik:"Yo im getting a forshit"
Amir:"how long do we have?"
Nik:"probably an hour before i have to shit"
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.