Nymphomaniac?

There's a reason that the "nymphomaniac" line got past the censors. It's the same reason that additional, similarly racy lines as well as the scene of Maurice measuring Jeanette's chest made it into the film: "Love Me Tonight" was a pre-Production Code picture.

That is, the film was lucky enough to be released a couple of years before the protests from the Catholic Legion of Decency about the bawdy content of Hollywood films resulted in a stringent enforcement of the censorship code. It was in 1934 that this enforcement took place.

For more information about the Code and the 1934 enforcement, here's a link to Wikipedia's entry on the subject:

http://en.wikipedia.org/wiki/Production_code

The gag is "NIP-omaniac".

In the early days they could get away with references if they were comedy. So they could have a funny play on words with nipomaniac, nymphomaniac, and kleptomaniac. It's what makes pre-Code movies so much fun. They were more adult. They assumed a savvy movie-going public.

In those days, "pinching" something meant stealing it, which is why the punchline that follows about the other guy's uncle pinching people on elevators works, because they're playing off two different meanings of the same word. Having said that, and considering "nymphomaniac" refers to hypersexuality in women (the male version of hypersexuality is known as "satyriasis"), you probably misheard the word they were saying.