When I was a kid, I ran elevators in Rockefeller Center in NYC, and often worked near NBC studios and Warner communications, so I've had conversations with tons of celebs. When Letterman (who I used to see regularly) was on NBC, he would occasionally have something called "the lazy show", where he would do the show from his office, while dressed in jeans and a t-shirt. There would be a dedicated elevator to bring the guests up. That night the guests were Teri Garr (very nice lady) and the comedian Richard Lewis. After I brought Lewis up, I took the elevator back to the main floor. Nothing was going on, so I went back up to Letterman's floor to listen to the show. When the door opened, Lewis was in the elevator bank pacing back and forth and talking to himself. I said "sorry", and went to shut the door, but he said, "no, its cool, I'm just getting ready for my apperance". We talked for about 20 minutes about stand up comedy and acting and how he readies himself, then we went off onto sports and politics and other things, until he had to go on. When the show was over, I took him back down to the main floor. As he left the elevator, he turned, put his hand on my shoulder, and said "hey man, thanks a lot, I really appreciate it" and left. What he was thanking me for I don't know. His stage persona is not far off his actual persona. That's just one example of the encounters I've had.