The Oatmeal has the story of how a web design goes to Design Hell to show you, complete with insane requests from clients.

New bulb joke I haven't told you before.

Q. How many designers does it take to screw in a lightbulb?
A. I think really the issue is not so much the lighbulb in this case, but the relationship between the lightbulb and the ceiling around it, and if were to introduce a lighbulb at this point, what knock on effect would that have on the room in general. A lightbulb in this context may seem like a small addition but in actuality could have an effect on the whole which will require a considerable amount of subtle work to be carried out on the general interior design which would, of course, result in budgetary issues for you. Not saying we couldn't screw it in, but best to establish a baseline for this at an early stage.