I had another idea. There is a knotted penis Lora but I didn't see one for barbs and using barbed/spiky penis added white spikes and was unstable. The knot is optional so just prompt for it as desired. I was able to run this at .85 strength and get pretty goods results so start there if you have other LoRas. For clarity, barbed_penis is the trigger word.

Example Prompt:

futanari, cowboy_shot, barbed_penis(masturbation:1.2), precum, smile, huge_penis, knotted_penis, large_breasts, cleavage, ejaculation, squatting, looking_at_viewer,

FYI as per usual this dataset contains zero men so if it works for men, great but I'm not testing for it.