That's the longest Internet-acronym i've ever heard. It does mean:

Rolling on the floor laughing biting the carpet dancing in circles and jumping through the window almost dieing by smashing into HP who's then running horrified into the street beeing killed accidentally by a yellow bulldozer.
A: woo! i'm the haxxor!
B: ROTFLBTCDICAJTTWADBSIHPWTRHITSBKABAYB
by Visor December 8, 2003
Get the ROTFLBTCDICAJTTWADBSIHPWTRHITSBKABAYB mug.