Stemming from the popular term "Wet Willy" where your friend licks his finger and shoves it in your ear, a Dirty Dale is shoving a finger in a friends ass and then inserting it into another friends ear, thus leaving a burning, stinking sensation.
a dirtyleg is a girl that loves to have a good time and it doesn't matter who with. She is the most hated girl at a party by the girls because most guys are flocking to her knowing they will get laid. Also someone you can call on at a short notice to party with. booty call
I called me a dirtyleg last night cause I was bored, and she got me stiff as a board! If you wanna get laid I know a dirtyleg we can call.