You didn't say if it has to be an ebook, so...
I enjoyed
Quite Ugly One Morning, by Christopher Brookmyre. If your sense of humor is as twisted as indicated by your request, you'll recall that this title was lifted from a song by Warren Zevon.
Review 1
Review 2
Gaiman and Pratchett's
Good Omens is a little lighter on the morbidity and a little heavier on the comedy, but is quite entertaining.