The University of Chicago Press gives away one DRM encumbered title each month. This month the freebie is Jokes: Philosophical Thoughts on Joking Matter by Ted Cohen.
Jokes is a book of jokes and a book about them. Cohen loves a good laugh, but as a philosopher, he is also interested in how jokes work, why they work, and when they don't. The delight at the end of a joke is the result of a complex set of conditions and processes, and Cohen takes us through these conditions in a philosophical exploration of humor. He considers questions of audience, selection of joke topics, the ethnic character of jokes, and their morality, all with plenty of examples that will make you either chuckle or wince. Jokes: more humorous than other philosophy books, more philosophical than other humor books.
You can go here to sign up for it. Downloading it will require Adobe Digital Edition.