A revenge tactic where a light fixture, or wall sconce is removed, and shit into; a globe style fixture is best.
The shit-filled fixture is replaced over the light, creating a dimly lit room, and the light bulb will begin to bake the shit, therefore creating an incredible stench.
Best used against a rival fraternity.
Fuck those DeltSigs man...let's go to their party and give them a Dirty Dim; then all the hot chicks will be grossed out and come to our house instead.
When you sleep with a leftover woman at the end of a party - all that was left at the end of the night was a dirty dim sim in a hot box at the local 24h servo.
"Can't believe you slept with that dirty dim sim last night Greg, that was just terrible"
"OMG I can't believe Greg went home with that dirty dim sim, she's trash"