I wanted to replicate the kind of butts I was able to generate with SDXL checkpoints like Lustify, so I trained a LoRA using a non-AI dataset of mainly face down ass up poses viewed from behind.
v1.0 is experimental; I trained it on 75 manually-tagged images for 5000 steps, but it's a small subset of the 300+ images I intended on using in order to test robustness. The captions were a mix of danbooru-style tags and natural language.
I think it works better for controlnet and img2img, but txt2img can output decent booty depending on how you prompt.