This is actually something I work on in therapy. My T is all about stopping, and taking deep breaths, and repeating calming self affirmations. The one I try to use is "I am calm and in control." It's definitely not easy. She also suggested I try going for walks or to a coffee place or something. But since i have a tendency to pick fights at night, that didn't work. I did go for a walk, and then to a bar where I sat and had caffeine free soda while watching the sports channel. It helped, but it's a hard habit to get into (deep breathing, calming mantras, and removing yourself from the area), especially when what we're already doing (picking fights, being mean, etc.) feels so much easier.