Most annoying champion to play on your team with? can only name 1.
Bard
Bard

And I know this because I mained Shaco, and felt bad about it even tho I was good.

NO! DON'T SPIT ME AT THE ---- (dead)
Never fail. The player is an asshole.

As a support main, I just hate having to support MF. I almost never can do well with her for some reason.
fugly champion is so hard to look at cuz of how ugly he is has to win toplane before 15 min or is useless for the rest of the game then starts whining and thinks he knows everything because renekton mains have a god complex :)!
his stupid gun doesnt work with ardent censer!!!!
if he dies 1 time in lane guarantee u will never see him again for the rest of the game!

FOR THE LOVE OF GOD LET ME OUT 
- Either they are good and take every kill, even the one you have just flashed and ulted for, or they are bad and go 0-5 and AFK/quit and are never seen again. Although it says I can only name one, I think there's a few other champions that fit the exact same criteria with this, especially certain junglers.
Completely selfish pick that demands a team be built around him. If he ever gets killed early in the jungle expect no pressure for at least 20 minutes. Late game they think they can 1v5 and end up throwing the game.