Ordinarily, upon sitting down to write a review of a guide to English language usage, I'd get myself pretty worked up, nervous about ensuring I didn't end a sentence with a preposition or forget what a semicolon is used for. Fortunately for me, Anne Curzan's Says Who? is a different sort of usage manual; its subtitle (A Kinder, Funner Usage Guide for Everyone Who Cares About Words) gives that away right off the bat. Yes, you read that right: Curzan uses "funner" in her book's title, and if that fact gets you ready to fire off an angry email to her publisher, maybe this isn't the book for you. Or maybe, on the other hand, it's exactly the right book to urge you—both playfully and persuasively—to take a different approach to our ever-evolving language.

Curzan is a professor of English, linguistics, and education at the University of Michigan. Many of the examples she ...