That was hot but should have been harder, perhaps a paddle or strap. I also think for further punishment for exposing himself he should be locked in a chastity cage
My MIL had no moral scruples in coming over to our place to give my butt a good whipping. She believed in performing at an empowerment ritual by sucking me off before paddling my bare ass. My wife loved watching, especially when I got my ass spanked with her hairbrush. If I was lucky she would stop with a hairbrush. Otherwise she would pull out her razor strap and really lay on the leather. Sometimes she even brighter riding crop so she could flick my back full of welts.