half-gasm 

when you're jacking off and you're not really feeling it yet but you cum anyways and you end up feeling horny again soon thereafter. usually happens when you're in a rush or about to get caught.

i was wacking it to some hot pics of jenna juggs 'til i heard someone knocking and i half-gasmed. total buzzkill.

half-gasm by silly hats only October 20, 2008

half-gasm 

When masturbating, holding back for too long and then letting go, only to find that you've missed the orgasm, but still ejaculated. Disappointing, all the work but none of the reward.

I jerked for 30 minutes only to be rewarded with a half-gasm.

half-gasm by ()*%^$#@&! April 4, 2006

halfgasm

A physical and emotional sensation experienced at the peak of an exciting situation that is roughly half as sensational as the sexual sensation resulting from the stimulation of the sexual organ.

This sandwich is so good it is giving me a halfgasm!

halfgasm by ianbrunner March 30, 2009

Halfgasm

The act of having an orgasm that doesn't give you pleasure. A small amount of cum is released, but the intial feeling of an orgasm is not there. Is normally the result of some bad internal timing.

Joe: How'd it go with Susie last night?
Bob: Terrible, I only had a halfgasm.

Halfgasm by King Singh December 17, 2008