Or, to be specific, dragon sex as it occurs in fantasy literature. In fact, what surprised me was that my wife though it was pretty hot. I don't know Donny or his wife, so I can't really speak to their backgrounds and reading habits. However, I think it's likely this is not the first time Mrs. TPK has encountered dragon sex.
I first ran across it when I borrowed my mother's Anne McCaffery novels. At the time, I thought they were wonderfully unusual novels, unlike anything I'd read before. A young person usually a woman is estranged or separated from a family that is not good for her. She forms a telepathic bond with an intelligent animal in this case, a dragon and with its help, begins to fashion a new, healthier family for herself. For and with this new family, she risks all to make the world a better place or at least save it from an impending catastrophe.
And, sprinkled within, was dragon sex. It wasn't very detailed, and actually read more like an aerial race where the males attempted to catch the females to prove their worthiness. It mostly served as a counterpoint to the relationships of the people.
Years later, I came across dragon sex again in the books of Melanie Rawn. This was something else entirely. Sex between dragons in her books was more like sex between sharks. It was primal and violent, and served in part as a metaphor for the clash between the chaos fomented by the greed of the villains and the civilized order the heroes were trying to establish. Dragon sex, however, is just the tip of the iceberg.
I've mentioned before the differences between fantasy novels aimed at gals and those aimed at guys. It's not just authors who are known for it, like Laurell K.
Arrow's Fall includes a rape. Now the ladies in the audience are probably shrugging their shoulders at all this. I might as well be talking about how grass is green and rain is wet. The thing is, even among authors writing for guys who are notorious for sexual themes, fade-to-black was the general rule. The erotic exploits of brazenly hedonistic pulp heroes like the Gray Mouser, Conan, and Elric were only alluded to and never detailed. Even Jack Chalker, whose prose could run hot and heavy right up to the act, would suddenly seem bashful as the event was efficiently mentioned and then passed through and beyond, where consequences would arise as the story resumed it's normal descriptive depth and pacing.
Again, my suggestion for guys who won't burst a blood vessel doing so, is to pick up one of these books and give it a try. You might hate it, but you'll likely be exposed to a style of storytelling you've never experienced before. Even if you don't have dragons carving notches into their bedposts, you'll find new ways to work relationships and similar themes into your games.
This was worth dragging up above the fold. Ursula Vernon did a great post on the antecedents of this subject, seen through the filter of fanfic. I did not, at nine, actually comprehend on any kind of level that homosexuality was something real people did. Like every other girl of my generation, I figured that out from Mercedes Lackey books, and at one point put down the book and went, "Um.
Perhaps inevitably, she also drew the odd creature of the subconscious that thrives on such psycho-sexually charged weirdness as dragon sex. She calls it Susan.