In the New York City college community, the symbol (y) is used in internet conversations as a symbol for a thong. As New York City sets trends for the rest of the world, this definition is soon to be used all across America and planet earth.
So it's not thumbs up nor boobs anymore. Get used to it.
Boy 1: I stalked you on facebook. Nice (y).
Girl 1: OMG, what does (y) means?
Girl 2: It means thong.