Many friends keep asking me today what exactly happened and how did it feel, and one of them even found the story very funny, so I am going to serialize it all here.
Flight with VM and Of[e]k, four people aboard Cheyenne which was just back from a test flight following a long overhaul. Climbing to work altitude of 21kfeet, with headphones.
At 19k, BOOOM and all cabin suddenly white thick myst. Plunge down wheee fast (some good lunapark for free), mayday call, the pilot R shouts for someone to bring him oxygen fast. I am thinking fast and manage to figure out where the oxygen is (it didn't drop out), put away the masking tape which was used to seal it (so it doesn't drop out too much) and give the mask to the pilot. R asking M to fix it. M: "fix it yourself, I am holding the stick". R: "Don't hold the stick! fix my mask!". The back side was torn so we had to hold it. Then flying safely to land at Sde Dov.
The experience: the decompression was obvious immediately. It felt like a decompression, some throat ache and a headache. A bottle of window cleaning liquid on the back of the plane started to spray all over the place, which was fun.