Anyway the guy may know this and just wants to mess with your head.
I feared this may be the case, I’ll bring it up in his next appraisal;
“We may need to initiate a formal performance review if you continue to exhibit such poor urinal etiquette.”
Or
“Stop splashing your piss and clapping your foreskin in the bogs you freak, or you’re sacked!!”
One or the other, not decided my strategy yet.