From Tanya Khovanova’s blog — one of my favorite math blogs. Do visit if you like math.
Once when I was working at Telcordia, I received a phone call from my doctor’s office. Here is how it went:
— Are you Tanya Khovanova?
— You should come here immediately and redo your blood test ASAP.
— What’s going on?
— Your blood count shows that you are dead.
— If I’m dead, then what’s the hurry?
Given that I wasn’t dead, the conclusion was that there had been a mistake in the test. If there had been a mistake, the probability that something was wrong after the test was the same as it was before the test. There was no hurry.