Books! Books! And Additional Books!
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When Homer and Marge noticed the spice fading from their love life, Marge decided they should buy a book to help them out. The next day, the family went to Books! Books! And Additional Books! The sign out front announced that the daily special was "Michener $1.99 / Lb."
While the kids went shopping on their own, Homer and Marge looked in the "Marital Relations" section. Marge didn't want them to be seen looking at books about sex, so they were embarrassed (and grabbed the first books they found to cover what they'd been looking at) when Bart and Lisa finished their shopping earlier than they had expected and caught them. Marge did reasonably well, albeit a bit awkwardly, ending up with a copy of Tanks of the Third Reich, but Homer wound up with a copy of Mapplethorpe and screamed when he saw the photos in the book.
The family ended up buying the following books from the store: