A Lusus is the guardian of any and most all trolls in the webcomic homestuck. A Lusus will pick any given grub in the brooding chambers and become their guardian, much like a Parent where as trolls have none.
Example 1: Feferi's Lusus Is The Biggest Lusus Of All, A Giant Sea Creature Which Is To Be Fed Dead Bodies.
Example 2: Gamzee's Lusus Was A Sea-Goat, AKA The Capricorn Constellation.
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.