Inside Jokes by Hurley, Dennett and Adams, Jr.

An enjoyable work of popular but sophisticated science that, as stated in the subtitle, uses 'humor to reverse-engineer the mind.' As usual, Dennett and Co. present a theory sketch, combining and extending other theories, offering their own insights and providing testable hypotheses and challenges to researchers. Given this is a book about cognitive science and humour, if you're into both topics, you'll like the book, if just the former, then you'll probably enjoy the fresh angle, and if just the latter, then you might find this a bit too detailed. 

Inside Jokes is full of jokes, some hilarious, many not, but all used to illustrate their analyses of humour and why we have it. Their many thesis is that humour (or mirth) is a result of the realization of a false belief and this process is 'paid for' in evolutionary terms as the fitness advantage rewarded to the organism that (generally) maintains more accurate belief structures. Secondly, there is nothing intrinsically funny of humourous in stimuli, but in the brain of the person who is amused or laughing. They draw the parallel to the lack of intrinsic colour in the objects around you as well as in your head when you 'see' colour, as the perception/experience is a combination of outside stimuli being coded/decoded in a certain way by your brain.

Although I would recommend the work, I'll reiterate the aforementioned caveat that it might be a bit thick and not the easiest read if you haven't had much prior exposure to cognitive science/psychology.