For some years now I've heard You're not the boss of me increasingly more often relative to the more "correct, natural" (to me, at least) You're not my boss. Thanks to the magic of NGrams, I've confirmed my suspicions that it's not just the company I keep…
At first I just thought the "boss of me" version was just a childish equivalent, but now I'm not so sure. If I extrapolate the graph (bearing in mind NGrams doesn't quite reach today yet anyway), it seems likely the new variant is already (or soon will be) the standard form. What's going on?
In case that's not considered a proper ELU question, I'll rephrase it as "What if anything do people perceive as different about the new version, which might be causing them to prefer it?".
Best Answer
"You're not the boss of me" emphasizes "me," and is something a child would say (or we imagine would say) to his parents. It's also often said by an adult to give the statement that connotation, sometimes in an ironic way.
"You're not my boss" is a bit more on-the-nose and declarative, whereas "you're not the boss of me" is more absolute, confrontational, and draws more upon the cultural shared knowledge of that phrase.