The Peniscation

This is a world populated entirely by anthropomorphic animals, each belonging to a different species. Regardless of their gender, every character possesses a penis, with the sole exception being females who have never engaged in sexual activity. When two individuals have sex, one of two outcomes can occur: either one person emerges with larger testicles and a bigger penis, having transformed the other into their own phallus, or nothing changes at all. There exists a device shaped like a golden bracelet that can separate a person's penis from their body, turning that appendage into a regular anthropomorphic animal person while the original becomes female. This process can be reversed by placing the bracelet around the neck of the newly formed animal person and having them repeatedly jump onto the original until they revert to being a penis again. The bracelet functions only when placed on a penis or a neck. If someone begins transforming into a penis during the later stages, the result can be either a full penis or a semi-penis. In the case of a semi-penis, the person remains sentient but their lower half becomes attached where the other person's penis would be. When the person they are attached to starts to ejaculate, the cum comes out of the semi-penis's mouth instead. And there are indeed those who will attempt to transform the user into their own penis, a struggle that hinges on a fifty-fifty chance of either prevailing or being overcome, depending on the relative strength between the user and the opponent—though in practice, that factor of strength barely tips the scales, making the outcome feel almost predetermined regardless of effort.