Someone who has the ability to mindfuck others. Someone who is stealth enough to complete missions with other ninjas that involve high risk situations. A ninja can usually "ninja" information out of other individuals who are clear 'un-ninjas'.

Ninjas are usually dressed casually, and people don't usually peg these people as actual ninjas, but rather, ordinary and normal girls. Watch out though, there couldbe a ninja at your workplace.

And she could ninja the shit out of you.
co-worker: blah blah blah blah blah

ninja: (in her mind) - good to know I just ninja'd the shit outta you bud. I'm going to go tell my other ninja this classified information.
by ninjatwoxo July 22, 2011
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An intense sexual position involving a man and a woman and a dildo, the way it is performed is
first, you turn off all the lighs in the room
second, you start banging the girl in the ass
third, you shove the dildo in her ass and pull out so she "does not know"
fourth, you jump to her side scream NINJA and punch her in the face.
Jenny:Damn, i got ninjad pretty hard last night.
Me: Yeah i fucking owned you
by JMANWASSUP August 19, 2005
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Adjective.

Basically another word for cool. Except cooler, as its the word Ninja. Similar to badass in defintion yet far more badass, i think the best explanation of this word is infact 'Ninja'.

This is going to happen. It's Inevitable. It's going to happen big.

It will grow and spread across the Internet like wild fire with a shuriken.
*Roundhouse Kicks someone through a wall*
"Woah that's so frickin' Ninja!"

*A very nice hat*
"That hat is so Ninja!"

*Walks on the grass when there is blatantly a sign with clear instructions not to*
"Shit, that dude is ninja."

*Prefers Pirates*
"What a queer"
by ThatNinjaguy November 15, 2009
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crazy ass mother fucker blackbelt who can whoop your butt without you even knowing they are there. Crazy skilled, stealthy, never seen. usually teens and mid 30s. Quick moving and very effective.
We are some of the most nastiest ninjas in the world.
by ray-cait-whatev April 3, 2010
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Ninja is a game in which two or more people must play. The game is played by slapping each other on the hand. You can only make one move per turn. Once an attempt at slapping the other person's hand is made, you must keep your body in that position until your next turn.
Person 1: Dude, my hand hurts from that Legit game of Ninja!

Person 2: Hella yeah it does, I pwned you in Ninja!
by Lavieta February 27, 2010
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n. A warrior originating from feudal Japan who specializes in the art of stealth, assassination, sabotage, and molesting people without them even noticing. Ninjas are around anymore, but the term can still be used to describe one who is very sneaky, clever, sly or just a bad ass in general.

Here are a few requirements a Ninja would have had to live up to when they were active:

1. Ninjas must be able to make themselves unnoticeable in a empty room painted top to bottom in white.

2. Ninjas must be able to remain submerged in water for up to 7 hours minimum.

3. Ninjas must be able to survive a one-on-one fight against Chuck Norris for 6 WHOLE seconds.

4. Ninjas must be able to hold in a fart for 3 months

5. Ninjas must have an 11 inch penis MINIMUM. THIS WAS MANDATORY

6. Ninjas must be able to stop their own pulse for up to a week.

7. Ninjas can read a person's mind and memories just by staring at them

8. If a Ninja is captured, they must find a way to kill themselves.

9. Ninjas are expected to be able to get a 100% on every song on Expert mode in Guitar Hero 3. Failure will result in immediate execution.

10. A Ninja must have watched and memorized Nigahiga's "How to be Ninja" video
Person #1: "Would you rather be a Ninja or a Samurai?"

Person #2: "Yes"
by superdawge October 9, 2009
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A Transmitted Disease Which Is Acquired By Either Having Sex Or Getting In Contact With An Infected Persons Blood aka The Ninja
Brian: Dude Help!
Angelo:What's Wrong?
Brian: I Don't Know Man, I Just Slept With Melanie!!!
Angelo: Dude I Think You Just Got The Ninja!!!
Brian: Dude I Can't Feel My Dick!!!
Angelo: Its A Good Thing I These Got Ninja Proof Condoms At Walmart For 7.99.
by Ibetatestedyourmother November 30, 2007
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