A girl with no pictures of her that expose much/anything below the neckline--the insinuation being the presence of weight or general body-image issues. The term can be altered for a male of the same nature.
A: Hey, how come this girl doesn't have any pictures of her whole body? All her pictures are just different angles on her face.

B: That one girl Tommy just started dating? Yeah, she's a neck-up girl.

A: Aw, man. Good luck, Tommy.
by Defnot January 13, 2011
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