Look, if you're playing a 4v5 as the team with the 5
Don't say GG at the end of the game.
Because whether you intended it in good will or not, you look like an ass to the enemy team, because I can tell you the enemy team most certainly did not have a good game. They had to suffer through 20mins of being handicapped, and probably died a lot because of it, and all in all the game was basically ruined for them.