pronouced nee-es, refers to the area of skin between the testicles and the anus. from spanish, "it is neither" because it is neither the balls, or the anus, but an area between. synonyms include: chode, gook etc.
"my girl found me making out with her sister, so she kicked me in the nies."
"that girls a freak, all she wanted to do was lick my nies."
"after a long walk outside, jose had a very sweaty nies."