What if?: serious scientific answers to absurd hypothetical questions, by Randall Munroe, is a collection of the best and sometimes worst of Mr. Munroe's blog posts on XKCD, an informative and hilarious web comic. Munroe started out as a NASA roboticist but I guess that job wasn't nerdy enough so now he draws stick figure explainers that explore science's quirkier side. He also got famous enough to have a star named for him,"citation needed" (that's an inside joke for after you've read the book). XKCD, by the way, is an unpronounceable (according to the author) word which is neither an acronym nor a word with any meaning.
The questions in the book and on the blog are user-submitted and the answers are researched