Puking on someone's genitals because he pushes your head down while you're giving him oral.
It tends to happen when drunk chicks with weak gag reflexes are man handled by guys who don't understand head etiquette.
"Oh man, he wouldn't stop pushing my face down so it was Dirty Jamaica all over again."
A variation of the Dirty Sanchez but for real ninjas. When conducting a Dirty Ninja the Ninja in question will take his penis out of his womans ass and wipe fecal matter all over her face leaving only the eyes visible. After you have accomplished this you must proudly proclaim out loud "Dirty Ninja" to be an offical Dirty Ninja.
ex. After having sex with my wife too soon after a delicious crave case, she was punished with a Dirty Ninja
WARNING: A Dirty Ninja is not to be taken lightly, loose peanuts or cornmay cause skin lacerations or eye injuries
The act of making yourself as fat and greasy as possible, and then forcefully fucking a girl in a bathroom while you have two friends guard the door. Consent is not required.
A: What happened to you at the bar last night?
B: I was busygiving some girl a dirty Roethlisberger.
This action is carried out when you are getting head from a girl you really don't respect. You first blow your load in her mouth because you don't care about her, then when her mouth is off of your shaft you cold cock her right in the jaw, making her resemble a very dirty boxer!
Last night I pulled the dirty boxer on a bar slut, it was magical!