I suspect many acronyms became poplular because of on-line chat rooms. You're having a real-time conversation, any you have to type everying - ick. It's not good for spelling and grammar, but it's faster. The acronyms and other shortcuts gradually crept into other places on the net. (I may be completely wrong - it's just a theory.)

It may drive u nuts - it's not 4 every1.

TTFN (ta-ta for now)