The day after a massive night, when everyone has not yet slept, and is still off their face, from booze, pills or whatever else was/is going round.

Dirty Dunday is a derivative of the song "manic monday" by the bangles.

The dunday gets really dirty when everyone starts singing "just another dirty dunday"
I punished a case of beer, ten pills and a gram of speed last night.Just another dirty dunday.
by gold member October 25, 2005
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