A slang term for "nasty". When one tries to enunciate "nasty" with a lame accent it may be mistaken for "nehsty" which has been changed to "neesty" to avoid any change in enunciation no matter what accent one may have; One who is "nasty" at something, metaphorically speaking.
Pat: Yo, Chad!
Pat: ........you're neesty you're neesty!
Chad: Y-Yeah i know..
1) a person who is not clean;
2) someone who doesnt have money; a bum;
3) lower class
Eewe, that girl is so neesty. she should probably shower.