The result of a woman shitting on a mans chest hitting his nipple and the act of him pressing a glass half full of water against it and shaking. The use of the liquid varies. Commonly called dnp and way more popular than you’d thing in the southeast.
When a boob is slightly under water (most bathtub scenes) and you can see a slightly discolored spot in the water where a nipple is hiding underneath the surface. Kind of like a cave dwelling spider, you knowit's there but you can't quite see it.
Blayne-"Chase rewind I thinkI just saw Amy Smart's water nipple!"
Chase-"Holy shit that is her water nipple!, man I love "Mirrors."