Don, maybe there is a lot of humorous music that you just never knew was
humorous...  you have to be tuned in...  There was once a musician at the
Utah Symphony who was also a professor of music named Martin Zwick.  He
took great delight in pointing out humorous classical works based on his
research and the symphony performances.  Paul Banham and pianist Reid
Nibley also spotted and wrote on the subject.

I really crack up over Beethoven's 8th, and I have always thought the march
in the 9th was humorous...  I believe Beethoven had some fun buried in his
cynicism as he continued to write music he couldn't really hear.

You have to listen for it.

Mozart, too, poked fun at music as he composed...  though his is a little
easier to hear than is that of Beethoven.

Ray Bayles