Ol' Al Einstein's been having to pay the piper and has been on the rubber chicken circuit for the past three months. It's the same damn thing every night of course and Al's about ready to punch his clock.
However, his chauffeur (who's been to all the lecture's and kinda looks like him) comes up with an idea.
"Sir," says he. "I've been listening to you give this same lecture for three months, why don't I give it a go tonight, and you take my place?"
Einstein agrees and the switch goes as planned.
That night, after a very successful delivery and even several well answered questions, the chauffeur's gambit appears to be called when this prof gets up and starts asking this long involved question. He's bringing in multiple coordinate systems, nth degree matrices to make sure that everyone knew he was on the ball.
The chauffeur gives the man a withering look, sighs, and then says, "Sir, that question is so elementary, I will have my chauffeur, who is sitting in the back, answer it for you."