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1.
The term used to describe the unpleasant odor of sweaty, unwashed testicles after a few days.
"Man I got to take a shower, I don't want Krissy smelling the nut funk"
by Matt December 05, 2003
 
2.
extremely foul smell from the bottom of the testes which results from streneous exercise, physical activity or yo nazzty ass hasnt bathed in a few
damn yo, you got sum nazzty nut funk, dawg
by jaime April 02, 2004