In the name of FUN, I'll pop this game down here.
The concept is simple: You make a wish, and the next poster responds with "Granted, but..." and stipulates a condition of said wish. Then they make their own wish.
EG: "I wish I could fly." "Granted, but you can only do so as long as you can hold your breath. I wish for a million pounds." etc etc.
I wish I had an eidetic memory.