look up any word, like sex:
 
1.
A person who can engage in sexual intercourse or masturbation so stealthily that the people in the adjoining room do not suspect a thing.
Dave: Dude, did your parents cath you and whats-her'face screwing last night?

Ed: No way, man. I'm a sex ninja.
by Wesker June 06, 2006
 
2.
The purpose of sex ninjas is to flip out and have sex without you knowing.
Then the sex ninjas flipped out and had almighty flying wall to wall sex while Kieth sat in his room, unaware.
by Freddie December 16, 2004
 
3.
To be totally awesome and sweet
Girl 1: OMG i just had the best sex0r ever
Girl 2: Really? how many times did you cum?
Girl 1: About 56 times in 1 hour, it was SO sexninja
Girl 2: OMG FAP
by The Romero January 25, 2003
 
4.
Someone who acts conservative but is secretly really kinky and good in bed.
"I thought John was a super awkward nerdy guy who never gets girls, turns out he's a complete sex ninja!"
by THE sex ninja December 30, 2012
 
5.
Someone who's sexual prowess is so awesome that they boarder on having mystical powers.
"They pulled a total Sex Ninja move and made me jizz using only their thumb!"

They must have gone to Sex Ninja school 'cause they fucked me balancing on one leg on the edge of the bathtub!"

"That Sex Geek made me cum so many times and in so many ways that their nickname is Sex Ninja."

"Sex Ninjas can make you orgasm anytime, anyplace."
by ReidAboutSex August 23, 2011
 
6.
Someone who is super sneaky in bed and doesn't get caught or noticed (Unless they want to be).
"I am a super sneaky Sex Ninja. I will sneak into your house, Into your room, Take what I want from you, Leave and you will never know I was there."
by C00kie Crumbs November 28, 2006
 
7.
a incredibly homosexual person who loves ghey mens
Guy1: Man that guy is such a wolfanoz
Guy2: no, he's more of a sexninja
by =D January 25, 2003