Check out How to Write Like a Cartoonist by Scott Adams to get an idea about how humor should be written.
By the way, Adams has quite an impressive blog, with posts that read like personal essays. In fact, I think that's what they are.
I'm the only person at Chez Gauthier who has never been a major fan of Adams' Dilbert books. Some family members would suggest that this is because it's been so long since I've held anything like a so-called real job. However, I would definitely read a collection of Adams' essays.