check valve 

Used to describe a selfish person. Commonly used by navy machinists. If a person goes to a vending machine and doesn't ask anyone if they want anything.

"Hey shipmate, how's the soda?" Thank's for not asking me if I want anything. Fuckin' check valve."

"Hey look at that nub over there eating McDonald's. I'm not signing that check valves qual card."

check valve by TorpMan, Submarines December 15, 2008

check valve 

A person who does not have the capability of seeing both sides of an arguement.

Following an arguement where the one person continues to not recognize that his/her point of view could not possibly be incorrect.... "Why cant you at a minimum see that the other side of the arguement could have some merit? You fucking check valve. You one way mother fucker!"

check valve by JP7 March 11, 2009

check valve 

Refers to a careful inspection of the positioning/operation of a new/replacement one-way flow-stopper to make sure it's being installed in the correct "direction".

Zero was too stupid/unaware/forgetful to perform a "check valve" detail when hooking up the plumbing for the Camp Swampy mess hall, and so now there are geysers squirtiin' up all over da camp, but no water coming out in any of the kitchen-faucets --- just something more for Sarge to bellow about.

check valve by QuacksO August 12, 2018

Mexican Check valve

A tiny little turd holding back What seems like 10 gallons of fart

I had to get to the shitter before that Mexican check valve went through my pants

Mexican Check valve by Fucko October 27, 2021