So if you are just pulling his pants down and not off all the way, the danger is them peeing all over themselves and you. Then you have a kid covered in pee and you might not have extra clothes. Hold him up with your arms around his chest and lean him forward about 45 degrees. He’ll have to be in charge of his own penis, just cross your fingers that he doesn’t spray everywhere or dribble. Try to pick a spot pointing downhill. Oh, and go behind something; there’s always some perve or other watching.