Kol Ra'ash Gadol provided an answer to my son's question. If he wasn't so young you'd probably find his response to be kind of rude.
Here is what KRG said:
Tell him that I told you that girls aren't jealous not to have a penis, because all out parts are neatly tucked away where they can't get hurt. And I'm a rabbi, so I can be smart about some things like that.My son's reply to this was to ask if she knew a lot about a penis because she had a father or brother. I didn't ask him to clarify, but it was clear that his disdain for girls overrode his respect for rabbis.
If you want to see something funny watch his face when you tell him that one day he'll think that girls are fun and interesting. Anyway, back to the matter at hand.
Son: I think that you are smarter than the rabbi.
Dad: I appreciate that, but it is not important to me.
Son: It is to me.
Son: Because you're my dad.
Dad: Thank you. But really it is not that big a deal.
Son: I get it. You think that the rabbi is stupid and you don't want to hurt his feelings. You are being nice.
Dad: No. I don't think that the rabbi is stupid.
Son: You told me that rabbis are people.
Dad: Yes, rabbis are people.
Son: Sometimes people do stupid things, so maybe the rabbi is stupid.
Dad: Yes, sometimes people do stupid things, but that doesn't mean that the rabbi is stupid.
Son: Can I ask the rabbi?
Dad: What do you want to ask?
Son: I want to ask him if he has ever done anything stupid?
Dad: That is not such a nice thing to say. You shouldn't ask that.
Son: You told me that I could ask the rabbi anything.
Dad: You can, but that doesn't mean that you should ask a question that is going to be offensive.
Son: What does offensive mean?
Dad: It means that some questions will hurt a person's feelings. So you shouldn't ask him those.
Son: Right, because if he is a stupid rabbi he is really going to feel badly.
Dad: No, because we don't want him to think that we are calling him names.
Son: Moshe's father said that the rabbi belonged in Chelm and that he wears ugly ties
Dad: That is not something that we should talk about. Moshe's father did something that wasn't nice.
Son: Your ties aren't as ugly as the rabbis.
Dad: I don't wear ties that often.
Son: I know, but they aren't as ugly as the rabbis.
Dad: Ok, let's get something straight. It is not nice to talk this way. We don't judge people by how they dress, just by what they do.
Son: But dad, he bought those ties and they are ugly. That is judging him based upon something he did.
Dad: Listen to me, this is not a conversation that I want to have with you. It is not nice and we are not supposed to talk about people this way.
Son: Can G-d talk to people this way.
Dad: G-d can do whatever G-d wants to do.
And before he could confound me with anymore questions I offered to buy him an ice cream cone. Sometimes that kid kills me.