GD in a Nutshell:
-NERF <X Champion>
-YOU CAN'T NERF <X Champion> BECAUSE <Y Champion> IS OP! YOU WILL REGRET THIS NOOBS!
-What if X was a female/your roommate/etc
-Lol All the People Who Think <X Champion> Is OP Are Bad
-Elo Hell, by struggling silver/gold player.
-Why Elo Hell doesn't Exist, By a Diamond Smurf stomping bronzes.
-I wuz unfairly banned by Tribunal but won't post my report card
-I wuz unfairly banned by Tribunal but my report card sez I'm a ****** come laugh at me.
-Riot Y can't we pick by role? I want to be support graves.
-pls implement voice chat so I can screech at people
-DotA2 es better trolololo
EDIT: Forgot a couple categories of topic.