Whats your lol pet peeve
Mine is dorans rings on supports :(

Mine is dorans rings on supports :(

ADCs who rush 
People who don't enchant their boots even after they're full build.
Especially ADCs not getting Furor.
Agreed, I will rag on and nag any doran ring/no sightstone supports. If you didn't want to support you should of just said so and I would of done it properly.
Also the only thing that actually makes me mad is my laners taking my jungle without asking first.
When someone selects Ezreal in champion select then in the last few seconds switches over to Ashe. Talk about a cock tease...
But in all seriousness I can think of nothing more irritating than instalockers who say nothing in the lobby then when the game loads up demand to go in X lane after that role has already been called. For instance, instalocking in amumu and then demanding to go mid after our Ahri already called it in lobby. Then the instalocker proceeds to feed and complain about how the jungler never ganks and then spamming the surrender button at 20 minutes followed by the inevitable rage quit after the team declines to surrender. Those are the worst.
ADCs who don't listen to my pings while I'm supporting and scream at me when they die to a Jungler's gank while I'm trying to get them to fall back.
warding would be the most obvious. BAD warding is even worse. Warding under their tower. Really?
and most recently. Sorakas that heal themselves to death
Them removing the 20 MS off coin.
Now it's harder for my Janna to get 520 passive MS