Venting your anger at a workplace

Probably all of us have had a situation where screaming, shouting, punching and breaking things were the best possible options, but not at that particular place and time.

Office. A place where people need to pretend they are nice to each other, though they'd love to stab you in your back when you're not watching. What I miss in the corpo world is that if something goes wrong, people will not shout you that in your face. They will sneak around just to make sure the knife is finally in your spine. When this finally happens, you would love to destroy everything, but since you wish to be regarded as a mentally healthy person, you accumulate your emotions deep inside of yourself, still wearing the knife of course. Such situations probably do not happen only in offices, but since I have experience with this kinds of environment, I will let you guys say something about your workplace anger relief techniques.

What can you do if you don't have a pillow you can scream into or don't a punching bag isn't around (and of course you are aware of your potential behavior consequences)? I realized that listening to metal music does the thing. Though I'm not a metal fan at all, I have to admit that I never thought it would bring so much benefit. If you're angry - play "angry" music. I strongly recommend Rammstein here.

Do you know any other ways you may vent your anger in an invisible way?!