I remember an early episode of Mission: Impossible in which Rollin (Martin Landau) successfully impersonated someone by using the latex mask bit. That was pretty standard, but the really unbelievable part was the fact that he mimicked the voice perfectly as well - and he had never heard the person speak.

MI was one of my favorite shows at the time, but when I watch it now, I really have to suspend my disbelief.

"Come with me to Canada. Toronto is just like New York but without all the stuff."