When you do the traditional run up to your buddy and while making a karate hand and jam it up between there legs in a reverse karate chop.
Effectively chopping their nuts hence the name squirrel chop
*runs up to buddy*
*Performs squirrel chop*
"Squirrel chop!!!"
You must say this to distract from how weird it is that you just put your hand anywhere near your buddies private parts. Also...don't make eye contact.