Booby vs. Bobby

So, I'm cleaning the kitchen as the boys are eating their pre-bedtime, no-sugar-added ice cream treat when I hear Zach say something about a 'booby.' Without looking at him, I ask him to repeat what he said to be sure: "This is Josh's booby." As I turn around to scold him for using 'potty words,' I note that he's holding the boBBy pin that Josh picked up in what is likely to be some gross, unsanitary place.

I quickly bite my tongue and gently correct him: "That's Josh's bobby pin, Zach." He looked at me like, "booby, bobby, what's the difference?" Yeah, ask me that in about 10 years and we'll see if you've figured it out....