What's worse is people who say for the win in real life. I learned about FTW that way because I go to a nerd college. This guy was telling me he runs Oblivion on high settings with his 7800GT and I asked how, he replied "mods for the win". He might have said "lawl" after that, I don't remember. After he said "for the win" a few times I asked him why he says that and he explained it to me. Were I playing Halo online as much as I did like 3 years ago I definitely would have known about this. Man, come to think of it I think I started one of these pieces of internet slang back then. I don't remember what it was, but I remember saying it in Halo for awhile and then sometime later someone who I never played Halo with said it to me (I don't think it was in Halo either). Anyway...FTW is dorky, just like most other pieces of Internet slang, but I don't even care anymore.
EDIT: The sad thing is that since I don't keep up with it all anymore, and some of these acronyms are hard to decipher so I have to Google them to find out what they stand for. Whether it's sad for me or sad for the Internet I don't know, but it is definitely sad.