This word originated from the abreviation :
ROFL = Roll On Floor Laughing.
Which is a term widely used in internet chatrooms and instant messaging software.
Roffle evolved due to people readling ROFL like a normal word rather than spelling out each letter as R. O. F. L.
Roffle is therefore the casual friendly way to say ROFL and can be used as a verb in its own right:
To totally destroy an opponent who had no chance of winning. This is most used in PVP video games and usually pertains to a situation where through either numbers, gear or some other quantifiable aspect of the game the outcome was a foregone conclusion. Derives from the internet acronym ROFL to illustrate that the victor is "rolling on the floor laughing" while defeating his or her opponent.
"I went into Warsong Gulch last night and got rofflestomped by a premade with all Season 3Gear."