Ninja Ass 

An ass that you cannot see. According to the person with this ass, it's apparently there, but not visible to the naked eye. This is just an excuse for a woman with a really flat ass.

Finneh: I caught some bitch looking at my ass a few days ago.
STEFFFF: maybe it was my ass
Finneh: What ass? OBRN!
STEFFFF: its there. =(
Finneh: So apparently you have a ninja ass.

Ninja Ass by Finneh January 7, 2008

Ninja Ass Blast 

Near the end of intercourse, the man pulls his penis out of the vagina and slips it into the girls ass and unloads semen into her rectum before she realizes what just happened.

Joanie's ass hurt after Frank gave her a ninja ass blast

Ninja Ass Blast by va jay jay king April 4, 2010

ass ninja 

One who engages in anal sex so quickly and stealthily that the other person is unaware that it has occured.

Bobby was in and out in 9 seconds. He is a true ass ninja.

ass ninja by FAH Q 2 January 20, 2006

bird ass ninja

a sensitive asian guy, an asian guy who likes birds

Leon is a real bird ass ninja, he gets upset when he is not svelte.

Leon likes birds, so he must be a bird ass ninja.

bird ass ninja by DrJK December 21, 2010

ass ninja 

ninja's that spontaniously spawn from ones ass.

'Goddam, i had a bit of trouble with some ass ninja's this morning.'

ass ninja by Prycey September 9, 2003

ass ninja 

A mythical being who exists to give people wedgies. As with the Tooth Fairy, Santa Claus and the Easter Bunny, the Ass Ninja visits all the little boys and girls in order to bunch their underwear at the worst possible times.

"Dude I totally just got visited by the Ass Ninja! Cover me while I pick my underwear out of my butt."

ass ninja by Dark_Angel August 25, 2012

Crazy ass ninja 

a rather crazy assed ninja, such as yoda, or chuck norris (also note chuck norris kills most failed crazy assed ninjas)

Daaaaaaym chuck norris is one CRAZY ass ninja

Crazy ass ninja by Crazy assed ninja January 29, 2009