Or at least know the formula that the author, Scott Adams, uses to ensure his comic is funny?  He calls his formula the 2-of-6 rule.  He gives a list of 6 elements that, in order for something to be funny, it needs to cover two of them.  This kind of sounds like a commercial I've seen but can't remember the product.

I won't give the list here since it is his work.  If you do click-thru you'll see that he compares two other comics where one cuts the mustard and one does not.  Funny stuff!