I really doubt it. My boys are smarter than I could EVER have thought any animal to be, coming up with intricate schemes and plans (this has been another debate: can animals plan...I'm sure most people would agree they can, to an extent). But I don't think they have senses of humor, at least the way we define it. My little boy is so playful and has a great sense of fun, and if you do something you think is funny (eg tripping down the stairs and laughing at yourself for it) he'll "smile" (dogs open their mouths when they're relaxed, which is a way of smiling), and will mimic my delight (becoming playful, wagging his tail) but he is simply responding to my emotions.