Theres a survey of humour reported on the bbc website which list "the worlds best joke":

"A couple of New Jersey hunters are out in the woods when one of them falls to the ground. He doesn't seem to be breathing, his eyes are rolled back in his head. The other guy whips out his cell phone and calls the emergency services. He gasps to the operator: “My friend is dead! What can I do?” The operator, in a calm soothing voice says: “Just take it easy. I can help. First, let's make sure he's dead.” There is a silence, then a shot is heard. The guy's voice comes back on the line. He says: “OK, now what?" "

Not bad, but not what I would call the world's best. I prefer the Aussie-Hunters-snakebite joke immortalised in a Castelmaine XXXX advert which is in the same vein.

I remember read in Edward de Bonos lateral thinking book, he analysed humour as being surprise resulting from an unexpected pattern in events.

The "Death by Mao-Mao" joke brought to life in the League of Gentlemen is also pretty good....

dave