Dress Your Family in Corduroy and Denim by David Sedaris
I, quite seriously, laughed until I cried reading this book of short stories. I also found that after reading this book I was part of (what seemed like) some secret club. At parties, if you recommend David Sedaris or refer to one of his stories, undoubtedly someone perks up and says "What about that story when he..." leading again to side-splitting laughter. I call it a book with lasting side effects.
This one gets a b+