I Don't Get This Joke From Dirty Rotten Scoundrels

I just saw the national touring company in Chicago and loved the play, but this one seems to be over my head:

(referring to writing a note to the character Doctor Shuffhausen)
Christine: Should I use an umlaut?
Freddy: No, you smell great!

It would make sense if umlaut rhymed with douche or perfume, but both are a stretch. What word does Freddy think she's saying -- or am I overanalyzing this and the point of the joke is that he's totally clueless?

He's just totally clueless.

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I thought it was funny. And the production was good.

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I'm seeing it tomorrow, and I'm excited. Are they selling any merchandise?

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Just exactly what part of "Jerry likes my corn" didn't you get? Jerry likes her corn. Simple as that. It's not a joke really. It's only funny because it's something as random as corn. I myself love the song and find it more endearing then hilarious.

Nougat.