LOL, LMAO, CDFU, ROTFL, etc.

It's come to my attention in the past two months (since I joined Twitter) that there is more than one way to abbreviate laughter.

"L.O.L.," translates loosely to, "I'm too lazy to type."

Since Twitter, I've found LMAO, easy enough, than CDFU (Crack Da Fuck Up) and now what I'm reading from more than some is ROTFL (Rolling On The Floor Laughing). I'm curious, is this all necessary? And if so, who wins?

AMMA: Abbreviations Make Me Anxious.