Skipped Parts ($5.99 US), by Tim Sandlin, is free for UK Kindle customers (only) in both the US and UK Kindle stores, courtesy of publishers Sourcebooks. If this follows the same pattern as others from this publisher, it'll be free for US and other customers in a few hours (after midnight in Seattle, at the earliest, is my guess).
UK link
Book Description
Banished to the hinterlands of Wyoming, rebellious Lydia Callahan and her thirteen-year-old son Sam have no choice but to cope. But while Lydia drinks and talks to the moose head on the wall, Sam finds a friend in local girl Maurey Pierce.
One of the wildest, raunchiest, most heartfelt coming-of-age novels of the past thirty years, Skipped Parts puts Tim Sandlin in the upper echelon of contemporary comic novelists.