Bath time is a short process for my son and I. I turn the shower on to get the bathroom warm. Then I go back to him and get him naked. When we return, he lays across my lap while I turn the shower valve to the bath, get his soapy water basin filled, and put his bath chair into the tub.
On this particular day, he was lying across my lap. I turned to shut the bath water off. When I turned back, his right hand had found his penis. He didn't make a big deal of it - no cooing, no pulling. It was as if it were a rattle or anything else he finds coming into contact with his hand. Pretty funny sight.