gfy is one that always got me into trouble...
To me, it's always meant 'good for you'. Apparently there's another meaning.
===
As for when to apply these epithets, I sometimes find 'nh and gg' particularly hollow - 'nh' in particular is extremely overused. I've even seen people who aren't even in the pot say 'nhs' when AA and KK comes out on the bubble - which if you're the one losing, is not a nice hand at all.
'gg' is also overused - to me it sounds particularly ironic if you've been playing badly and gone out early, for a whole bunch of people to start telling you what a good game it is... now that you're not in it any more.
I generally reserve 'nh' for quads or better, or sometimes for when I've made a bad call against someone who has a better hand than I gave them credit for. I reserve 'gg' for final tables, if at all... unless someone I've just knocked out says it to me first, in which case I might say it back out of politeness.
In getting knocked out - if I wish to be magnanimous - I generally wish the remaining competitors good luck (gl) which is my waying of signing off, and is to my mind the most unambiguous of these sayings.
Or I might just say nothing at all - usually because I have to rush off somewhere and scream at the walls. Please don't take it personally if that's the case...
