initials for "Girls Change You" as apposed to saying "bro's before hoes" or anything of that nature. it can be used as a noun, verb, or adjective.
person 1: hey, is chris still talking to that girl?

person 2: yeah i'm getting pissed he's becoming a GCY

person 1: i hate when my friends are GCYing
by toystoryking1599 March 28, 2010
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