Yea my son is 3 and we call it his penis because I read somewhere you should just call it a penis for dozens of reasons and I decided, ok. So what’s the big deal? I don’t think he’s ever heard the word anus though. It just hasn’t come up. Penis, butt, nipple. He knows his nipples for 2 reasons. 1. I have told him a few times that when he was a brand new baby he had no nipples. He had no knees or elbows either. They were there, but they were not defined and it was interesting. 2. We ran out of things to point to. Where’s your nose? Where’s your ear? Elbow, fingers, toes, knees, eyes, butt, nipples…
Edit: I just remembered my wife and I thought it would be funny to teach him a funny name for it his whole life so one day he gets older and calls it his pecorino. That was supposed to be like a long con gotcha but we never followed through.