Its a painful action that contains two males. one will use his hand open to drag it to the other's groins, or testicles, or nuts, then keep his hand dragged in. then he will start adding pressure on the nuts as he twist in his hands. This action keeps for 15 seconds minumum.
It's cool, try it out and record it on youtube.
Man, once in the camp i was sleeping when both my friends came in the tent and ductaped me to the bed i'm sleeping on, then they woke me up by a perfect nut squeeze that i screamed so that all the camp students and coaches may hear. the tough captain came in released me. he ductaped both my friends after hanging them a wedgie on the tree. and each member in the camp gave them a good kick in the balls. they deserve it although they're my friends