To achieve great result in image generation, please make sure to use descriptive and accurate prompts for better results. Prompts like, "pissing in urinals", holding cock while urinating", would yield better result and shows better representation of how a male should take a leak.
For Sampler, you can also try: DPM++ 2M Karras/DPM++ SDE Karras with similar or better result than Euler a.
You can play around with different Checkpoints but I find that Illustrious have better results than using Pony Base Models.