Patience, fake it if you must.
1) When you're on the phone, and someone is pissing you off, excuse yourself for a minute in a polite manner. Grab the nearest pillow, scream into it, and start off on the phone with your nicest "hello, where were we at?".
consequences: if the other party was also pissed off, he/she might get agitated with your smooth move, and say something worse to piss you off. hey, its not really fair to them that you seem to be taking it lightly and not feel the "intensity" of that heated debate.
2) In public, distract yourself. Eg. Look at the sky, and play "Accidentally in Love" or any other song that lightens your mood, in your head. When you're all cooled down, ie. your heart is not raging, and you stop feeling like punching a wall, start a whole new conversation, eg. So what did you eat today for lunch?
consequences: the other party might think you have an attention deficit disorder.
3) In front of friends or people you don't want to show your temper to, talk about that incident that you haven't recovered from laughing too much about.
consequences: third parties will think of you as a pointless nostalgic.
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