World of Patchcraft is a game you play after you have installed a retail boxed version of WoW.
In order to play the game you need to have the latest patches installed. Everytime you try to play WoW it checks for updates. When it finds that you do not have the latest version the game will download and install the patch.
This process takes almost forever and is refered to as playing the World of Patchcraft.
No life #1 : "So are you gonna join our clan?"
No life #2 : "No, I am stuck playing Patchcraft."
No life #1 : "Jeez, what speed is your internet connection?"
No life #2 : "Not sure but it is so slow I call it an intersphinkter connection!"
No life #1 : "That sux, lets rather play Megaman on my NES."
No life #2 : "Yeah, thats much more enjoyable than Patchcraft."