A man follows a woman out of a movie theatre.  She has a dog on a leash.

He stops her and says, "I'm sorry to bother you, but I couldn't help but notice that your dog was really into the movie.  He cried at the right spots, he moved nervously in his seat at the boring parts, but most of all, he laughed like crazy at the funny parts.  Did you find that unusual??"

"Yes," she replied, "I found it very unusual ...because he hated the book!"