ninja fuck 

1.To have sex without a sound
2. To have sex without the other person knowing

You had sex last night! I didn't even hear it!
Yep, I ninja fucked her hard.

ninja fuck by Frickin' Genius April 25, 2016

ninja fuck 

To penetrate another person without that person having knowledge or noticing.

Person 1: Whoa what was that?
Person 2: You just got ninja fucked!

ninja fuck by mario420 September 6, 2006

Ninja Fuck 

When you ( a male) is having sex with two other people ( male or female) and you fuck them in the butts back to back. Hence, you see an ASS, you see an ASS, and you went IN, or assassin ( which is a word used to describe a ninja).

Joe Schmoe: Hey bro, I just had a consecutive buttsex with these two smoking hot chicks last night
Douchebag Dan: Duuuuuude! You just had a Ninja Fuck!!!
Joe: Totally gnarly dude!!

Ninja Fuck by Jdawg96 December 17, 2013

ninja-fuck 

To have sex in a quick and intense manner.

"I could tell by the look on her face that she got ninja-fucked last night."

ninja-fuck by Jordy-Time February 17, 2006

Ninja-fuck 

To be completely silent during any type of intercourse

(Friend A) "did you have fun with John Smith last night?"
(Friend B) "It was alright, but he Ninja-fucked me and im not into that. It was so quiet you could hear crickets!"

Ninja-fuck by BlowholeJoe June 28, 2023

Ninja fucked 

To have sex in an extremly fast, violent, but pleasurable (for both parties) event. The idea of "Fucking like a Ninja" is to get in, out, and off, before you can get caught, be it by parents, angry spouses, or even the police, in some rare occasions.

She got ninja fucked, dude. Right after they both got off, he was gone like a goddamn shadow.

Ninja fucked by Andrew Flanagan March 4, 2006

ninja fucker 

Guy who likes to screw chicks violently and fast, like a ninja, sometimes in a public place. The girl is usually someone the "ninja fucker" has just met.

Man, after that quickie I had in the bathroom at the bar I feel like a stealthy ninja fucker!

ninja fucker by StinkyTee July 28, 2006