A trollercoaster is a word used to describe a common phenomenon on the interwebz. You see trolls (people who cause controversy for their own entertainment) often end up trolling other trolls. This results in a glorious uneducated discussing of pure controversy where everyone is ending up trying to anger one another, thus resulting in many trolls trolling trolls that troll trolls. This ladies and gentlemen is what we call a trollercoaster.
(trolling is a direct derivation from the word troll and is a verb used to describe the attempt to cause controversy for no other reason than for the posters own enjoyment)
Pete: Hey Jim I tried to troll a guy yesterday, but it turned out he was a troll. Other people joined in and tried to troll me aswell as trolling the guy i originally intended to troll. They also trolled one another.
Jim: Wow that must have been one hell of a trollercoaster ride.