I say "gg" at the end of every game I play. If the game is obviously going to end with me winning (eg 6 VPs left and I have all the victory points) I'll say "gg" as a sort of "thanks for the game".
Because COH2 has post-game chat I feel that players should surrender immediately if they "gg" and not remain in-game to chat. That way the other player can talk afterwards if he wants, or he can go straight back for another game.
Also, it doesn't cost you anything to be civil.
