I don't mean like trolling in allchat or flaming people. I mean what is the most borderline over the top thing you've done in a game to win?
For example, in season 1, I played Eve exclusively. I had her hovered in a lobby before a ranked, and somebody was spamming a ventrilo link. Since Eve was notoriously unpopular at the time, I got queue dodged a lot, so I copied the link, and sure enough somebody said 'wtf eve gg' and dodged. The queue then immediately repopped, and on a whim, I used the guy's ventrilo link and listened to their champ picks, and sure enough, our enemy team was the same team as the one on Ventrilo. Only 4 of their teammates connected, so they just assumed I was the fifth teammate, who happened to turn out to be their worst player.
So I then inform my team in chat of what happened and told them to listen to everything I say and we would automatically win. Naturally they didn't believe me at first, but I was duo at the time and we proved it pretty quickly. Their adc, the player who didn't connect to ventrilo, started feeding horrendously as I camped her. The other guys in vent started being like "Dude come on pls play safe", and I would just respond "yeah sorry my bad". They were mechanically really good, and it was definitely a change in the usual types of teams I faced. I have no doubt we would have lost without our advantage.
So they started coordinating ganks through vent, and I would show up every time on my eve, and my team would always be around to follow up and counter gank. They were all getting so pissed off in vent "HOW ARE THEY ALWAYS THERE WHAT THE FK", until they finally lost after trying to sneak a baron.
After we ended up in the end game lobby, they all talked shit to me in vent thinking I was the feeding ADC and blaming the loss on me, and I told them in vent what happened, and that I was the Eve on the enemy team, and the one guy who was hosting the channel just went silent. After about 30 seconds he finally said "You son of a fu--" then I just disconnected. I had never felt such a surge of guilt yet hilarity at the same time.