Stress is a pattern

Part of the pattern of stress is that of being very serious. The stressed person sees the source of their stress as a very serious matter which demands that the listener respond in a similar fashion. How can this pattern be broken?
My son, a prison officer, was telling me of a riot he got caught up in and how his friend had been taken hostage. I totally mis-read his emotion as he was re-living the experience. At the same time I realised that he needed to break the intense emotion and begin to look at the situation from a different view-point. He has always considered me to be very bright but somewhat impractical. I used this to break the pattern. In the middle of his intense emotion, I told him how I had gone to put petrol in my moped and how I thought the engine had seized because smoke billowed from it as I tried to run the engine. I told him how I had contacted my mechanic who in turn took the moped away. I told him how the mechanic had called me the next day and informed me that the engine was ok but that I had simply put diesel in it instead of petrol. My son started laughing and confirmed his impression of me with some un-printable words.
I then asked him about the riot. Now the intense emotion was gone, he could speak about it more objectively, from a different view-point. If the intensity returned, I just had to say "moped" to create a pattern break