I guess it's a generational thing

Just back from delivering Peter's birthday present. He's not home, only his dad is there. Here is part of our conversation.

Peter's dad (hereafter known as Paul or P): Should I hide this?
Me: Why?
P: He'll want to open it.
Me: He can't open it until his birthday. And that's the word with the bark on it.
P: What?
Me: That's the word with the bark on it.
P: What's that?
Me: Haven't you ever heard that?
P: No.
Me: (Incredulous) My mom and dad said it often. Did I never say that when you were growing up?
P: I don't think so. What does it mean?

I told Paul what it means. But I'll leave it to you to figure out. Shouldn't be too difficult. I wonder if you have heard it. I didn't make it up.