An enormous and/or monstrous poopie that is taken in the morning after a long days digestion.
To best encourage a successful Big Dirty one must recite "Big Dirty" multiple times. How loud one can say "Big Dirty" is up to the speakers discretion. This repetition can also be used to invite others to perform a successful Big Dirty.
Reciting "Big Dirty" can also be used to set an uncomfortable tone in any crowded restroom, public or private.
Stall 1: "Big Dirty, Big Dirty, Big Dirty"
Stall 2: Inhabitant leaves the restroom due to uncomfortable atmosphere.