With the Nunu "Support" Debate going on I decided to talk about what is "Meta" and "Trolling"
To understand "The Meta" we must understand "Standard Lanes"
Standard Lanes: Solo Top (Usually somewhere between a tank/fighter) Solo Jungler (Usually either an assassin or a bruiser/diver) Solo Mid (Usually either a Mage or Assassin) ADC Bot (Almost always a Marksman) Support Bot (Either a Utility/CC Mage or a CC Tank [and recently burst mages])
Meta: Following the standard lanes, with current known good picks, or champions you are really confident on.
Off-Meta: Following the standard lanes, with either currently bad picks, or a strange champion for that position but may still work.
Trolling: Not following standard lanes, or picking a champion that CAN NOT work in the lane you take them... without proper co-operation from teammates.
Essentially if its DRASTICALLY different, but your teammates are fine with it its not trolling. But in the Nunu "Supports" case he WAS trolling.
Apparently he basically told his ADC "Take a safe pick im taking smite and counter jungling" and didnt hear objections. It was also the only support strat he did. THIS IS TROLLING AS HIS TEAMMATES DIDNT WANT NON-STANDARD LANES. Thus putting them at a disadvantage, ESPECIALLY if the ADC isnt used and isnt prepared to 1v2.
However say i duod with a friend who went Top. And i get into game and say: "Hey I have a plan. Im duoing with this top, hes going Darius, and im going Blitzcrank. ADC can you pick a safe champion so we can 2v1 top, get first turret, then I'll roam? Jungle you shouldnt really have to worry about top unless you want that First turret gold too, and can you help out our ADC as much as you can?" And if they agree we went non-standard lanes without trolling.
The Nunu example WAS him trolling, although he may have not meant to, he ended up forcing his teammates into a severely off-meta to the point of being troll tactic and as people say, "Held his team hostage"