It's generally hard to get Stable Diffusion to make "a thin waist". The waist size of a character is often tied to things like leg width, breast size, character height, etc.
This is meant to fix that, to the extreme if you wish.
Simply add to the prompt as normal. No Trigger word is necessary.
V0.5 is far superior to the other versions. You can scale the weight between -2 and 2 without artifacts.
For hentai cases you may prefer the shape of waists generated by V0.3
Do not use version 0.4, 0.2, or 0.1 except for recreating old images.
Different versions have different formats:
0.5 Locon (Kohya)
0.4 Locon (LyCORIS)
0.3 Lora (Kohya)
0.2 Lora (Kohya)
0.1 TI Embedding
You can use this model anywhere without crediting me, but please take a moment to post some of your artwork on this page so I can see how to refine it further for the next version.