The Anima base model doesn't understand the reptilian internal penis concept. This model is my attempt to get something that works for a few projects I've been working on. It's been working okay-ish for me with the following:

In positive prompt: dr4gp33n, genital slit, penis

In negative prompt: testicles

This is a pretty shaky model, so don't expect great results. I'm sure it'll be replaced with something better by me or someone else soon.