Combination of multiple acronyms for laughing; an excessively long acronym for laughing to the extreme.
Literally means: Rolling on the fucking floor laughing my fucking ass off until I fucking die from lack of fucking oxygen.
Person A: Dude, I just saw that asshole that stole your board do a major faceplant in the middle of a street full of traffic.
Person B: Rotfflmfaouifdflofo!!
Person C: Call the ambulance! he is gonna die from lack of oxygen!
Person A: Damn, I didn't mean to make him laugh that hard.