I have had two rear blow outs/rapid deflation at speed, 70mph plus both last year and i have never had a flat before. I checked the tyres and there were no signs of punctures. I was leaving for a 6000mile trip and i was worried as i could not find an obvious problem with the tyres.
It turns out that the motorbike which i had purchese from a dealer the month before had been fitted with the wrong size inner tube in the rear tyre, ie they were smaller than they should have been. When the tube was pumped up to the correct air pressure for the tyre, it would cause the tube to stretch thus making the rubber thinner, this coupled with a high speed blat on the motorway and the rest is history.
I had the first puncture on the way to Manchester from last year Horizons meeting, in the middle of Derbyshire. Funny enough i had had Ultraseal put in the tyres at the Horizons meeting from the Ultraseal stand. I fixed the puncture with some pucture seal and had the tube changed in Manchester. The guy in the tyre shop took the tube out looked at the size and replaced it with the same size. It was only after my second blow out,when i called the breakdown recovery guy out that the problem came to light. he was changing the tube in the back of the van and he said 'You have the wrong size tube in this tyre mate' it all made sense then. I have not had a problem since.
I don't know if the Ultraseal helped by making it a a controlled deflation, but i did get a warning because i felt the bike twitch on both occasions whilst i was riding. There was more of a slight tear in the tube than a small puncture.
So if you run tubes on your bike check your tube sizes, it may be the cause of your rapid deflation.
Getting back to your original question, i agree with Bruce's answer and let bike come to a halt under its own steam........and then change your underpants.