The fun with this sort of joke is to choose a profession or whatever and challenge someone to devise a new ( or appropriately recycled) joke.

Here's one I devised (the only one I can recall at present - the rest are at home):
How many double-glazing salesmen does it take to change a lightbulb?
Well, with the manager's special offer, the easy-pay rebate, and the introductory discount, I'm sure you'll be pleasantly surprised at the final figure.

Taking my life in my hands, as for all I know there may turn out to be as many double-glazing professionals on this board as there are Daves; double-glazing selling is a standard joke in UK for the persistent telephone calls, and the peculiar pricing strategies. What professions fill this role in your country?

Rod