Clear or coloured liquid in a small glass bottle that can be painted on your nails. It's mainly a girl thing, but quite a few guys do it to...
Depending on your opinion, it can make people (both guys and girls) look better or some people prefer natual.
Becca: omg, Jess, you see that guy with the black nails...whoa he's amazing! Do you recon I have a chance?
Jess: Urrg! No way, he's proberbly gay!
Becca: Bet he's not... Hey, lad with the black nails, fancy getting a drink.
Guy: Yeah, sure =)
Bob: Bill you see those girls over there, the one's with the pink nail polish, omg, they're right tarts, everyone knows plain is sexy.
Bill: Yeah man, you said it!