So my 9 year old son was talking about something over the weekend. He used the words, "Epic Fail". Together as you might intend. He's also previously exclaimed, "Oh Em Gee". Literally those letters instead of "Oh my God". He doesn't play online games, other than say Webkinz. He doesn't have a phone. He doesn't IM or even email. It's all second or third-hand electronic internet infestation.
IMHO, if he says, "WTF" I'll either ROTFL or PWN his 1337 allowance.