For ROTFL, needless to say.
Or not. Fucking Wikipedia doesn't have a helpful entry for ROTFL (at the moment, if you search Google for "ROTFL" you find a whole bunch of definition pages, but if you search for "Wikipedia ROTFL" you get a stupid first entry about some ironic album from a random band, and then an entry about Internet slang that doesn't actually mention ROTFL in any useful way.)
Incidentally, you should read Mike Smith's LiveJournal if you've read, or will read, or will never read, the last Harry Potter. He's reviewing it chapter by chapter, and the comments are unmissable.
