Anger management!

get high

Scream dirty words.

kill your parents?

own 2 keyboards - one for playing and the other one for beating the shit out of it when you're angry.

Huehuehue

Wait for your 13th birthday.

Shock collar

I don't play LoL anymore.

Analyze why you get angry. Whether the reason is cause you lack something and need to improve or it's something you can't change, getting angry over a game really is a waste. I used to get angry when I got overwhelmed by enemies and what not, but then realized It's not their fault.. they just want to win. So do I. So it's my strategy that needs to change. So piece by piece I stopped raging at games and instead improved strategies. Basically learned to enjoy games.

I used to be like that. 1 Trick did it: I stopped caring about it.

And yes, another way is to smoke weed, it calmed me down too.

Realize that it's just a game and not worth losing your shit over. You could start by narrowing down why you get angry in the first place. Is it because things don't go the way you want to (especially in team-based online games), or does the game not function the way it should? I find these kind of things that I have basically no control over harder to accept than things I can control. For example, I the only times I found myself raging when playing Super Meat Boy where the times when the game glitched and killed me without any apparent reason. I didn't mind having to attempt a single level countless times because it was completely up to my own skills and abilities to be able to proceed, but when the game got unstable and consequently unnecessary hard for completely wrong reason, I got very annoyed.

But anyway, if you constantly find yourself bashing things and shouting at your monitor, it's probably best to have a little break whenever you notice the first symptoms of an incoming rage wave. And as I said, identifying the source of your frustration is a good first step to figuring out how to get over it.

Fact:
Being angry in games is due to lag. So the solution is to get a better connection :P

Not really but in my case the best thing is just to take a break and play later.

Stop playing games

Stop playing Dota 2.

I get angry all the time when playing games, and the only way to calm myself, is to physically hurt myself. I can't help it, really, but it's better than destroying furniture of items such as keyboard and mice, which actually costs money.

tnx everyone 4 suggestions, now i know it
WEED is answer to all my problems( im not even being sarcastic)!

Only play LoL with friends.

Switch to a different game or do something else like read or maybe even go outside.. and read.

I use to throw controllers and smash mice when Id run into a long streak of gaming luck. Now I often just laugh it off and give my monitor the finger.

Just take a 5 minutes break when things start getting ugly.

Don't be mad, basically. Remember that it's just a game, and it has challenges which you couldn't pass on the 1st try. Accept your imperfection.

Go to sleep.

Why do you play games? To have fun.
If you're not having fun, stop playing the game. Don't continue playing and start raging, just quit.

Make yourself realize that its's not just a game, and if you loose the match your house will explode and so will you and your parents. After 1 hour of your death the world will explode. (Sarcasm ends).

You really just have to realize that it's just a game, and if you loose a match your house won't explode and neither will you or your parent, and the worlds won't explode. (Reality ends).

Try yoga or something... Games are supposed to be fun, not make you angry... :s