Chazz's Bangin' Birthday (A Hypersexual Diary: The Adventures of Mr. Curvy, Chapter 70‪)‬

Ron is an admitted hypersexual- someone who is obsessed with sex and feels compelled to engage in frequent sexual activity. As an independent consultant and as an instructor at a local community college, he has the opportunity to meet thousands of young women- and many of them wind up naked in his bed.
Although solidly in middle age, he has a rock-hard body and a rugged look, emphasized by a beard and tattoos on both arms. Due to his compulsion, he has had sex with hundreds of women in all manner of situations. Over the course of these adventures, he has learned something about how to give a woman pleasure, heightened by a unique anatomical feature. An old girlfriend bestowed the name “Mr. Curvy” to it, and that name has stuck.
Evoking classic pulp paperback porn of the 50s and 60s, the Mr. Curvy stories are accounts of some of Ron's more recent adventures, and are true stories of real sex with real girls; they actually happened exactly as they are described, except that the names of the women and other characters have been changed to protect their privacy.
In Chapter 70, The pretty graduate student is one of Ron’s favorite playmates, and so, when she tells him it’s her birthday, it’s time to for a special celebration: She wants Mr. Curvy to be her very special birthday present, in their own private little party, before she goes out to celebrate with the rest of her friends.