Overwatch's new sniper mum hero Ana, it turns out, has secret trolling capacities. Ana's "Sleep Dart", which makes enemies unconscious for a few seconds, can actually render a player inactive and kicked from the game. If you collect three Anas around an enemy and keep that enemy constantly asleep, that player will get removed from a match. You'll need three, since two Anas can't maintain a perma-sleep considering the dart's cooldown time.
A video of this was posted today on Reddit. Three friends and I confirmed the mechanic in a custom game.
This perma-sleep hack is hard to pull off in Quick Play, since enemies will be going after the trolling Anas. Additionally, it's impossible in Competitive Mode -- there's a one hero limit. It doesn't seem like there needs to be any sort of change made to Overwatch, but it is pretty funny to watch.