An object lesson

[princealbertofb]

But that young lady, is right; we didn't have the "green thing" back in our day.

Because there's a comma missing. Now corrected.

There should actually be two commas, so that THAT is no longer a demonstrative adjective but a demonstrative pronoun. Haha, I didn't read it that way, at first. But, of course, you're right. It works better that way.
But that, young lady, is right;