There is a misconception this side of the pond that Americans do not understand irony.

Then I watch The Simpsons, listen to some of the American comics making a good living over here such as Reginald D Hunter and realise it is an urban myth.

Mind you, I do have one observation based on experience. Emails over the years have always had people copying on jokes. I can always tell when a joke has American rather than British origin.

There is usually a superflous line after the punchline, normally along the lines of "and she fainted" or similar. In other words, describing the reaction to whatever the punchline is, rather than leaving it to the imagination, (the more British way of telling a joke.)

I'm not making a judgement call here, not comparing to prefer one over the other, although I am far more wired into the British style. Just making an observation. I was in The Netherlands a few years ago and my Dutch colleague said that there, the best jokes don't even go as far as a punchline, but describe a scene. He gave an example of Gulliver in Lilliput needing "relief." The lilliputians formed two lines of coffin bearer formation and picked up his dick. "Forward! two three four, Back! two three four, Forward! two thr......" He had tears as he was saying it.