Anal impalement with a unicorn horn.
Someone else shared this, and the Unicorn erotica reminded me of this:
The Carnivores - The Series - 4 Dinosaur Erotica Books: Gay Dinosaur Erotica (University of Dinosaurs)
Warning: This is gay erotica and involves sexual encounters with dinosaurs. It is very explicit in sexual content and detail. Please use discretion when enjoying.
This complete set includes:
Compie Gangbang - B.D. Whitney
Magic of the Dimetrodon - Slade Hardin
Seduced By A Sabertooth - Slade Hardin
T-Rex Master - B.D. Whitney
There's a lot of weird fetishes in erotica.