When you pull down your pants but have shorts under them and let some random dude stuff your asshole through your shorts while listening to people say," Go and sit down" and "oof"
A Dirty Julia is preformed when a woman goes from reading poetry to unexpectedly sucking your cock, caressing your balls, and swallowing your jizz only because she enjoys watching you cum in her mouth.
She does a dirtyJulia in such a way that no other sex will ever be adequate.