Mid-west country-folk (see hilljack) slang for nosy or prying. (Gladys Kravitz syndrom from _Bewitched_)
Every time I pull in my girlfriend's driveway, I see that nibby neighbor of hers lookin' out her window.
A small sexual organ, aka a small penis.
Mike Piquet in Nibby's Gone Wild.
I'm allergic to the bar tender. Every time I see her my nibby swells up.