David and I are watching a video online together when I receive an instant message from a friend, which makes a noise.

David: What’s going on here?

Me: My friend Lauren just IMed me.

David (frowning): I don’t even know what that is.

Me: Instant message? You’ve never heard of it?

David: Oh. I have, I’ve just never seen it happen.

He’s only a few years older than I am, but he’s from a different generation…