Fixed/altered version of my previous upload. I cropped the output, removed the multiple horns, fixed the proto-nipples on his balls, hand-drew in a bit more precum, and exaggerated his smile a bit.

The Process: I made the above changes at 512 resolution and ran the changed image through img2img for 55 steps at 30-50% strength until I found something I was happy with. Then, I upscaled and added finer details by using img2img at 1024 with 10-25% strength for a few iterations, making very minor alterations by hand in between iterations (to the eyes and hair in particular). Finally, I did one final img2img pass at 1024 for 155 steps, upscaled that to 4096, then downsampled to 2048 for the final image.

Challenges:

• The image got more saturated than I would have liked while doing my img2img runs.
• The increased saturation resulted in his areola having less definition.
• He also lost a few of his spots while doing my img2img runs. I'd really like him to have more spots without needing to hand-draw them all in.
• Bovine characters seem to have troubles with keeping only two horns. The model kept trying to add two more small horns between his current horns.
• Large balls tend to generate nipples on the front, possibly because they're visually similar to breasts and pecs.
• The large brown spot on his left pec tended to become a nipple, too.
• He's not as fuzzy as I want him to be, I wanted him to have a large tuft of fur between his pecs, but the model doesn't like doing that.
• The model is confused if penises come out of bellybuttons or not.
• He kept losing his ears between img2img runs.
• His arms/biceps are a bit wrong-looking. I couldn't really get it to look much better, though.

Prompt:

barzoku, muscular_male, anthro, belly, abs, bull, pecs, biceps, bovine, realistic_shading, fluffy, chest_tuft, detailed_fur, 4k, large_penis, huge_balls, hyper, spots, detailed_background, bedroom_eyes, looking_at_viewer, smiling, smirking, precum, happy

(Yes, I did typo 'barazoku' with the prompt I gave to the model, d'oh)