Dirty Thirty

Slang term: A person's 30th year of life. Typically a 30th Birthday term representing one surpassing their 20s to enter the "dirty" part of life. Adulthood. Dirty 30 celebrations tend to be a night full of drunken debauchery. Full of bad decisions, vomit, and unnecessary semen in random places.

"Marrisa is turning 30 this year."
"Ooooh shit. Goodbye 20s. Time for a Dirty Thirty party!!! No black lights. I still have cum stains on my jeans from Stephanie's dirty 30 party last year. "