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 7, 2006
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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 29, 2006
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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
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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 17, 2004
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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 31, 2013
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A hero for the new world, he brings about peace through the ancient art of Surprise Sex. His true identity remains a secret.
Oh My God, that guy was just attacked by the Surprise Sex Ninja.
by Innocent Bystander September 11, 2004
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Some fool with a t-shirt on his head, runs around and violates people (usually men).
Random Person 1: Cool look, a Ninja costume.
Random Person 2: That's the Surprise Sex Ninja.
Random Person 1: Why is he dry humping that guy's ass?
by Lacrox September 19, 2004
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