>>11352288
>a boner behind bars, against the bars, pleading with someone beyond the bars
Can do. I'm putting a tail wag in too, because I like kemonomimi.

>>11352766
For future reference, you'll get much better advice if you post a catbox of what you're doing - trying to help with just vague info about what you're doing (instead of an actual attempt) leaves lots of open questions.
What model you're using is hugely important to framing the advice.
>I'm trying to make a human futa on slimegirl scene
Pov or a 2girl more fullbody scene? I'd use different approaches for each - I'd use regional prompter for a 2girl gen, but would probably skip it if you're doing pov.
Some of the onahole stuff I was helping an anon with last thread is relevant. My catbox in >>11349596 has some prompting metadata that includes some of what you'd want for a partially-visible penis.
>"human futa,slimegirl"
'human futa' doesn't really mean much to the models. The dataset is trained on danbooru tags (illustrious) or danbooru AND e621 tags if you're still on pony or if you're using noobAI.
If it's not actually a tag there, it probably won't do what you expect if you include it in your prompt.