The grip you have when you grab some guy by the testicles, hence having a "handful of nuts". Agonising for men, it is a source of endless amusement for onlookers and passers-by. Another form of this term is "going the squirrel", which means that someone is attempting to grab someone else in a squirrel grip.
Person 1: This guy picked a fight with me the other day, but I got him in the "squirrel grip" and he sure changed his tune quickly.

Person A: This guy attacked Sophie in a dark alley, so she "went the squirrel" on him and escaped. Poor bastard'll be singing high-C from now on.
by Big Bad Mark January 31, 2005
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The act of placing ones (usally a mans) testicles in your hand and squeezing them is hard as you can, in attempt to inflict an intense amount of pain on the victim. This action is a very rapind movement and is NOT in anyway sexual.
Archibald: Oh my god that hurt!

Henry: What happened?

Archibald: Tony laid the Squirrel-Grip on me!
by NeverTHEless. October 1, 2010
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The act of holding tightly ones nuts, usually for a long duration. Primarily associated with occurring during masturbation.
"Bob couldn't hold a hammer today after a long night of squirrel gripping."
by Homer Szechual December 21, 2011
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