Giving an instant orgasm by quickly jabbing one's sides near the kidney on one or both sides at once which causes involuntary movement and sometimes unnecessary noises...
Boy 1: I'm going to give that kid an insta-gasm guys...

Boy 2: (After he was given the insta-gasm) (yelling) IT'S SO INSTANT!
by shadow1337 May 23, 2009
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When you see something or feel something that causes one or more of your senses to orgasm.
Guy 1: *Sees extremely hot girl* *Insta-gasm*

Guy 2: *Eats bacon* *Insta-gasm*

Guy 3: *Hot drunk girl falls on top of him* *Insta-gasm*
by HCTKPR July 18, 2011
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