ROFL is an internet accronmym for Rolling On Floor Laughing, and like all things internet it has adapted to nerd culture and has taken on new real-life use, though usually in a satirical way.
ROFL can be merged with other accronyms to created super l33t
acronyms that "r0x0r y0ur b0x0rs" per se. Some examples of the merged accronyms are as follows:
ROFLAARP: Rolling On Floor Looking At Assorted Rodent Pornography
ROFLEW: Rolling On Floor Laughing whilst Eating Waffles