Clean It Up Grandpa

In the car on the way home from playgroup:
Jack: That man on the radio said "hell" in the song
Me: Just don't listen to it
Jack: Okay, I will cover my ears. Mom, why can you listen to it and I can't?
Me: Because I know that I shouldn't say those words.
Jack: Grandpa says those words
Me: Yes, but you shouldn't
Jack: I am not going to say those words because I don't want to be old like Grandpa
Me: Grandpa isn't old because he uses those words
Jack: Then why is he old?
Me: Because he has lived a long time.
Jack: Why has he lived a long time?
Me: I don't know
Jack: I thought you knew everything?
Me: I do.
Jack: Were you lying to me?
Me: No
Jack: Then why has Grandpa lived so long?
Me: Because he is a good person.
Jack: Then why does he say naughty words?
Me: I don't know
Jack: Remember when you told me that you know everything? You lied to me!
Me: Look! There's a squirrel...
Jack: Don't change the subject!