Sense of Humor and the Self-Exclusion Fallacy

At work today, someone made a lame, strained effort at humor. Seeing his joke fall flat on its face, he fell back on this old chestnut: "Don't you have a sense of humor?"

Response: I do. Don't you? It's precisely because I do have a sense of humor that I'm not laughing.

The speaker was indulging in a common fallacy—the fallacy of self-exclusion. That is, the speaker gets to say whatever the hell he feels like saying without being held accountable for any kind of basic logic or common sense.

For example, how often have you heard this gem: "Nothing is black or white."? Oh really? What about what you just said?

Then, of course, there's this common stand-by: "You can't be sure of anything." Are you sure about that?

You get the idea.