B.H.
Is he peeing in his pants? like an accident then they're could be a medical problem and seek a dr.'s opinion but.....
if he's unzipping and aiming to pee on all these weird places I'd say he definately has some behavioral problems and would make him clean up his messes and do more than a timeout that is completely unacceptable and gross. That would drive me crazy I feel bad for you. Maybe he is doing this for attention.
My daughter at age 4 liked to be weird sometimes and sit on the toliet backwards and try and pee like a boy and I think it was a phase and curiosity and I explained to her if she stands up she will go all over my floor and her legs and she got the point. Some kids just have a curiosity.