Playing since season 1, just had the most offencive game

I have to say, out of all of the years that I have been playing League, I've never had a game like this. Considering that this consists of 3-4 years worth of playing, I think Riot has been doing a good job discouraging this kind of behavior.

Typically at the start of the game, there might be a few jibes here and there, but this game, the opposing Xerath starts insulting me due to the fact that I have a Viegar skin. Tells me to not get skins for champions I suck at, and that he played Viegar in the LCS. Later on stating that "He, is Xpeke." Which I find ridiculous. I mean, its always "possible" that I could be playing against a smurf, but ANYONE that played in the LCS would have out CSed me, controlled the lain better, and outplayed me harder.

If it was just him acting like this through out the entire game, it wouldn't be noteworthy. Rather, the entire opposing team, except perhaps the ADC, trashed talked to us the entire game. This of course worked, upsetting my team into raging to the point that the Skype host closed the connection. They eventually started to trash talk back to the opposing side. Which, of course, encouraged the enemy team to insult more.

By the end of the game, I think six or seven out of the 10 players in that game were insulting and trash talking in all chat. Granted, I chimed in commenting on if the Xerath was from LCS, I would have been crushed, and asked why they felt the need to insult us. But that was about all my interaction with the enemy team.

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Logically, I guess I can see why people behave like this, but I don't understand why people feel the need to behave like this.