Ninja Masturbating 

To covertly masturbate in the presence of others without their knowledge.

"At the bar I tried to listen intently to my friends at the table, but I was ninja masturbating and needed to finish off quickly."

Ninja Masturbating by ZombiUnikorn January 25, 2009

The masturbating ninja technique 

When a gentlemen decides to enter the masturbatory stage of his day, he may decide to deploy the homo sapien style (standing up) only to realize his t-shirt drops down into penile range. To avoid ejaculate or any lubratory means being transferred onto ones personnel, the ninja technique is engaged by whipping the front flap of the t-shirt over the head to create a warm, stylish, and protective measure against the army of unbelievable stickiness.

Policeman 1: "We found this fine young lad frozen to death here in the arctic tundra'.
Policeman 2: "It looks like he's been out here for weeks and missed the warm soothing touch of a woman, and decided to literally take matters into his own hands".
Policeman 1: "Correctomundo. If only he had a mentor to teach him the ways of the masturbating ninja technique, he might have pulled through".
Policeman 2: "Hey! Yeah that's true. If only he kept his shirt flipped over his head with his shoulders covered instead of taking it completely off, he'd still be here today".
Policeman 1: "Poor, poor, uninformed bastard".

The masturbating ninja technique by dirk digglett March 31, 2015

Ninja Masturbation 

Masturbation (by a man) that takes place silently.

Harry has Ninja masturbation skill!!

Ninja Masturbation by e4r5t6y7u8i9o0- November 25, 2010

Masturbation Ninja 

One who can masturbate/masturbates everywhere they have gone/are without fear of being caught, with any object, without being seen, heard, or others having suspicion of the action of masturbation, any where, any time, and any place.

Student #1: Hey man, I whacked off in biology today.
Student #2: HOLY HELL! Did you get caught?
Student #1: Hell no I didn't, I am a freaking Masturbation Ninja.
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Guy #1: I jizzed all over my friends moms bra last night while he was in the same room.
Guy #2: What!? He didn't see you?
Guy #1: Shit no, he was sleeping.
Guy #2: Good thing you're a Masturbation Ninja.
Guy #1: Damn right.

Masturbation Ninja by gregmastersensai November 20, 2009