1. Stay Calm.
2. Give the peson the benefit of the doubt. Example, a friend could tell another friend, that her cat got run over and the other friend just ignores her. She tells her again and she ignores her. She gets very angry. However, if she looks closely - her friend has got earphones on listening to music and didn't hear her friend speak. (Hope you got that strange scenario. Lol)
3. Leave the vicinity, otherwise if its husband and wife - there might be flying saucers in the kitchen.
4. If you have to speak to them - don't raise your voice, it will only get higher and then you'll get all upset.
5. Do what I do, have a big bar of Chocolate!