1 definition by Wesker
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.
Ed: No way, man. I'm a sex ninja.
by Wesker June 7, 2006