A form of "rolling on the floor laughing", except used in an arcane way, as a ways of the person laughing knowing something the person being laughed at, doesn't. (Made Famous by Sandy Mehglich of the "You Suck at Photoshop" Series)
Doris stood, puzzled, when Richard roflcon'd because knew that no one would ask her to prom.
A hostile spawn in the Minecraft mod Hack/Mine. It's body is made of Creeper heads, and though an idividual head explosion is less than the normal explosion of a normal creeper, if the whole thing explodes it's more powerful.
It is quite fun to watch new players get startled by the Roflconda's sudden appearance and scream while trying to hit it only to have it explode in their faces.
"AAAAAH WHAT THE HELL IS THAT!?" Honeydew of the Yogscast seeing a Roflconda for the first time before it explodes Xephos.
"OH MY GOD THERE'S ANOTHER ONE!" Honeydew again as another Roflconda shows up a minute after the first and blows up Xephos and LividCoffee.