There's a DVD with commentary?! I have to run out and buy/rent it!
Graves said that he thought shooting on the film would end when he uttered the line, “Have you seen a man naked?”
Was it in the script? I've heard that the studio interfered in the movie production, but why was he worried they'd shut down filming after that line?
One thing I read (but am not sure it's confirmed) was that the Zucker brothers wanted to use a prop plane in the exterior shot -- a homage to Zero Hour (their inspiration for Airplane!). The studio refused, so they dubbed in the sound of a prop plane for every exterior shot.
Graves thought that a grown man saying that line to a boy would have the censors all over them. Also, he wasn’t sure it would be perceived as funny. Then, there was an advance screening at the director’s guild and the audience roared.