The best thing you can do in this game is troll hard as you can, but don't say a word.

The people who start all the shit in this game are the ones who NEVER get the ban hammer, especially if they are in pre-made ques. Riot defends troublemakers and bullies non-stop. They ban the people who stand up to the bullies and stop taking their bullshit. The best thing you can do that I've found is to feed so astronomically hard that it is borderline intentional feeding. Dive that Alistar Kalista under their turret while pinging like crazy for your bot lane to come with you... dive that Lux mid while your mid laner is praying to God and pinging that you don't dive her. They will eventually start to rage and all you do is hit the report button and laugh all the way to the bank as the notification comes up that they have been punished.

This is my new goal is to get as many people banned from the game as possible since Riot doesn't give a shit about anyone except making sure they take really good care of the assholes in the game.