<JoeyTribbz> A stats professor plans to travel to a conference
by plane. When he passes the security check, they discover a
bomb in his carry-on-baggage. Of course, he is hauled off
immediately for interrogation. 
"I don't understand it!" the interrogating officer exclaims.
"You're an accomplished professional, a caring family man, a
pillar of your parish - and now you want to destroy that all
by blowing up an airplane!" 
"Sorry", the professor interrupts him. "I had never intended
to blow up the plane." 
"So, for what reason else did you try to bring a bomb on
board?!" 
"Let me explain. Statistics shows that the probability of a
bomb being on an airplane is 1/1000. That's quite high if you
think about it - so high that I wouldn't have any peace of
mind on a flight." 
"And what does this have to do with you bringing a bomb on
board of a plane?" 
"You see, since the probability of one bomb being on my plane
is 1/1000, the chance that there are two bombs is 1/1000000.
If I already bring one, the chance of another bomb being
around is actually 1/1000000, and I am much safer..."
