Onanism 

Colloquially it is a synonym, but technically the "Sin of Onan" for which it is named for is actually an instance of coitus interruptus.

"Onanism -- it's a hands-on job"

-Ghost, ENTER THE MATRIX

Onanism by Jay Jay Ron March 20, 2008

onanism 

to wank,
to tame the one eyed monster,
to make the cyclops cry,
man's favourite outlet,
a date with mrs palm and her five
lovely daugters,
toss yourself off,
etc etc

"now on the subject of onanism...we dont want to find you hunched double on the sofa bed pumping your fist" (league of gentlemen)

onanism by pinkpill December 1, 2004

Onanism 

from New Latin onanismus, from Onan, son of Judah (Gen 38:9),
masturbation, coitus interruptus, self-gratification.

Jon can'g get any, so he practices onanism.

Onanism by El Cid June 21, 2003

Onanism 

Ejaculation outside the vagina.

I think someone did onanism in my coffee again. That sure aint milk.

Well you would know scab mouth!

Onanism by Anonymous September 17, 2003

onanism 

the act of masturbating

that boy is so onanistical
he is havin a blast with that onanism
My pito is ready for its ony time

onanism by mexican't101 February 25, 2009

Onanism 

The withdrawl method of birth control

(removeing ones penis before reaching orgasm)

-not an effective method of birth control

Lets do onanism tonight hunny

Onanism by dude August 24, 2003

Arboreal Onanism 

Masturbating in trees.

Prior to killing Martha Moxley, Michael Skakel masturbated in a nearby tree. He was convicted of 1 count of arboreal onanism.

Arboreal Onanism by TwatCop September 23, 2005