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1.
The act of stuffing one's testicles into there partners anus. Usually a sexual act.
Her ass was so loose I could give her a nut stuff whilst my cock was in.
by +PF- July 03, 2005
 
2.
Nutstuff is the act of thrusting so hard into a girl that your nuts get stuffed inside her as well.
I was with my lady last night and I performed a perfect Nutstuff on her!
by D-Li Llama February 08, 2010