When is it okay to tell tall tales at the lectern?

On my personal blog, I weigh in today on Glenn Beck’s recent white whopper about having held the George Washington inaugural speech in his hands. Generously, perhaps, I attribute his speech-giving gaffe to an absence of a background in journalism, where he would have learned to fit the facts to the story (as opposed to changing the facts, or making them up).

But to my rhetorician friends, I see a different question to be asked, about when it actually is OK to tell a fib at the lectern.

Have you ever written a white lie into a speech? Told a personal anecdote that was exaggerated? Used a yarn that was probably apocryphal?

Let’s have some examples, and let’s debate: Was it OK?