It stands for "giggling quietly to myself"; Used during IM conversations in place of lol because no one really laughs out loud when they write lol anymore

Also used when something is just not hilarious enough to warrant a lol, a lmao, or a rofl.
Kristen: I tripped over my own feet yesterday.
Jack: gqtm
Jack: I hope you're ok.
by Echoreyn August 29, 2007
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