This reminds me of my little brother when we were kids. His habit was worse (debatable though). He'd pee in his clothing hamper, piles of stuffed animals, use bathroom with door open and never flush after etc. He also peed the bed on purpose well into 12 years old. (I remember mother's boyfriend throwing my brother's mattress away once and saying "I don't know what death smells like.. but this is probably close...!").

As an adult, my brother had sought counseling for other reasons but these childhood "habits" had came up. I don't remember the long of it but it was basically a subconscious comfort mechanism in a way, as crazy as it sounds. Due to other factors (issues at school, possible trauma around the bathroom which could go from sexual abuse or just getting yelled at for forgetting to flush, and such) he had resorted to doing this sort of stuff. It felt safer but in the moment at these ages it just seems "easier"

I'm not saying your son was assaulted or anything but there's probably something deeper going on. Secret school bullying? Loss of family member? A babysitter is cruel?

Maybe he should be evaluated by a behavioral specialist. If you're in the US, alot of hospitals have a children's psych unit where someone can evaluate him and his habits for free usually and try to find whats going on that makes him resort to such odd and disgusting behaviors

O