Random Summoner Name (ALL): Please report
I understand that you have had a bad game, it happens, but that does not mean that you should not say 'GG' to the people you are playing against. Heck, you could of said:
Random Summoner Name (ALL): GG for you, BG for us. Please report.
If you said that, I might consider reporting the player you had issues with. The idea of saying GG in all chat is kind of like the idea of lining up after a 'Tee-Ball' Game and saying Good Game to the opposing team. It's called Good Sportsmanship.
I know I have had some horrible games and have done this, but recently, I have seen how much of an ass I look like when I do that. It makes you look bad and (even worse) it makes the community look bad.