I be mature about things and handle it without being obnoxious or rude. I've had countless people literally scream in my face, or over the phone, it's like water off a ducks back to me now.
When it comes to online, I go grab a coffee, or have a short break and come back if things are real bad. There's just no real need to be rude, and it gets you nowhere. Other than even more worked up.