The argument about ain't being a word or not is an interesting one, and I can certainly relate to having that debate with friends in elementary school. It's funny how we were strictly forbidden from using it in class, but it was a staple of our playground vernacular.

And, as you mentioned, it's not until the inclusion of ain't in the Webster's 3rd International Dictionary that all hell broke loose. It goes to show the power of dictionaries in shaping our understanding of language, and how it can spark heated debates about what is and isn't "correct".

I'm definitely intrigued to read more about the history of ain't in David Skinner's book, it seems like it could shed some light on our society's attitudes towards language and how they evolve over time.