Another name for a prowler (a vehicle in Halo 3). Any vehicle That hovers slightly off of the ground. Other vehicles from the Halo series that can be deemed a roflsled are the specter from Halo 2 and the Revenant in Halo: Reach.
Some people even use a sort of chant while in a roflsled as they approach someone they know theyare about to splatter; "rofl rofl rofl rofl"