This from my two year old... Braden has been a little obsessed with his penis these days. What man isn't, right? But since the diapers came off, every potty experience is "quite the experience".
I see no harm or shame in letting him explore. I certainly want him to be comfortable in his own body. But sometimes he grabs his penis so hard that it turns purple. Now, clearly I don't have one, so I can't say for sure, but squeezing that hard can't be good for it?!
I don't want to discourage him from touching himself, so, without judgement I let him know that its okay to touch it, but add, "You may want to be more gentle with your penis. It's very important. You'll want to use it some day for more than going potty."
To which he just looks at me and continues to squeeze it, making him giggle.
Today, after his bath, he got onto the potty and, with a firm grip, he starts squeezing his penis until it turned purple. So I say, "Braden, why do you sometimes squeeze your penis so hard?" He looks at me with the sweetest smile and says, "Because I like how it feels. It feels good, Mommy!"