"Wgat" is an specific way of saying "When girls are tea-ing". Girls will generally make friends with a drunk, dead, plant while having copious amount of tea.
Girl #1: You know what?
Girl #2: Wgat
Girl #1: I concur
wgat? means "Who Gives A Toss? Always used when you couldn't care less about the subject at hand, or you think something is totally irrelevant to the discussion.