o-ring 

1. (slang) sphincter
2. (normal) a rubbery gasket used to seal a connection between two pipes. The o-ring is squished between two flanges, forming an air-tight seal.

Don't push too hard or you'll bust your o-ring.

o-ring by Khashishi April 20, 2010

O-ring 

Anal muscles.

1. My O-ring is a virgin.
2. If you don't slow down, you'll blow my O-ring!

O-ring by The nazi of Yatzee November 7, 2002

o-ring 

1.
performed when a girl, especially a bitch, is sucking on your balls; the man, or receiver of the nut-sucking, proceeds to smack the bitch across the face quite hard. But, it is a failed o-ring if the cock smackage does not cause the bitch's, or the balls sucker's, ears to ring. The most effective o-rings will knock a bitch out cold.
2.
to perform an o-ring.

1.
Bruce Lee: That chick jessica keeps giving me shit about her being pregnant but i didnt even stick it in the bitch!
Jose Contreras: Sounds like she could use an o-ring... knock that bitch out and she won't come back to complain to you anymore.
2.
Jose Contreras: Man, I o-ringed that bitch so hard last night she was out for an hour!
Bruce Lee: Thats nothing, ese. I once hospitalized a bitch I o-ringed her so hard.

o-ring by benny b from the bronx November 10, 2004

o-ring 

A small plastic seal used in paintball guns and on the valve of some paintball CO2 and HPA tanks.

The last time I took my tank off I blew an o-ring.

o-ring by nuage August 26, 2003

o-ring 

A circular metal ring for something to clip onto or fasten to.

The collar had an o-ring for a leash

o-ring by Psi Sushi November 8, 2003

o-ring 

A fleshy piece of skin removed from one's penis upon circumcision. Usually worn on a chain around one's neck, symbolizing coolness off the heezy fo' shizzle.

"Yo dog, dat 98,127,364 Carat o-ring is da shit fo shizzle. WERD!"

o-ring by Harvester August 19, 2003

o-ring 

(n) the moment of most intense pleasure in sexual intercourse

Whitney's excitement was so intense, she had an o-ring.

o-ring by O-ring Giver December 28, 2005