My customer recently discovered what is URL Rewriting, without completely understanding what it is, how it works and the pros and cons of it. Now, he asks for lots of strange changes in actual requirements of current projects and changes in old projects in order to implement what he believes is URL Rewriting.

On one hand, I'm annoyed being asked to do things which doesn't make any sense instead of doing real work. On the other hand, I can't tell my customer that he doesn't understand anything in the subject despite his interest in it.

I think many people have had situations when their manager or their customer just learned a new buzzword or a new technology, and he loved it so much than he wanted to use it in every project, everywhere, rewrite the whole codebase just to use this new thing, etc.

Also, I've recently read something related on Programmers.SE where people told about their experiences when there was a huge buzz around XML, and some managers would ask to introduce XML in every project just to show to everyone that they have used it.

So those who have been in similar situation, how have you managed it?