The Boy is developing a nice little sense of humor, with pretty darn good comedic timing for a 3-year old. It's really endearing, to watch and to listen to him develop along those lines.
When I read The Boy a book, I always try to get him to memorize and to repeat the names of the authors. He knows that "Where the Wild Things Are" has story and pictures by Maurice Sendak, that Batman was created by Bob Kane, that "If You Give A Mouse A Cookie" was written by Laura Numeroff, and so forth. Writers are important, you know?
The other thing I try to do is to have The Boy fill in words while I read. In "Where The Wild Things Are," which might be his current favorite book, he plays the part of Max and takes all of Max's dialogue in the book. For instance, I'll read: "His mother called him 'WILD THING!' and he replied," and The Boy will say, "I'll eat you up!" It's a fun little way to keep him involved and engaged in the story.
(Side note: since we started doing that with Little Bear, he's started to learn lots of stuff earlier than The Boy. I'm sure The Boy could have done this at this age, but we didn't do it with him.)
So, The Boy requested "Where the Wild Things Are," and I said, "Story and pictures by..." and he replied, "Bob Kane!" We chuckled a bit, and I asked again. "Laura Numeroff!" he replied, confirming that it was intentional. He was telling a joke!
The funny bit? For the entire story, he read all of Max's dialogue by saying, "Laura Numeroff!" I didn't let it phase me, and I read the rest of the story as is. We laughed a lot about that.
He's really a very bright kid. I'm impressed by how his sense of humor is developing - it's as much a sign of intelligence as anything else!