12. Held Captive by the Cavemen (2012)
Author: Shoshanna Evers
Promotional synopsis: "Ellie's been pushed back in time by her vengeful ex-lover. Now a tribe of frighteningly large, muscular, and very sexy cavemen are holding her captive. And they *all* want a turn."
We checked. No female on Earth finds this scenario appealing. We were going to point out there is nothing romantic about the title either, but one online commenter was quick to clarify that this book "is clearly labeled as not a romance but a gangbang." Duly Noted.