Where does sexy ass come from?

Sexy ass, for an “attractive butt,” starts popping up in the written record in the 1960s. Phrases such as tight, sexy ass were used in quite a few books in the early and late 1970s.

Also in the 1970s, we begin to see sexy-ass used as modifier. The -ass, here, is an intensifying suffix originating in Black slang, e.g., You have a sick-ass sense of humor or That’s a big-ass car. Compare badass.

Also in Black slang, ass can serve as a slang term for a person, so a sexy ass could be a “good-looking person,” e.g., Let me tell your sexy ass something. We can find hip-hop artist Drake using sexy ass in the Weeknd’s 2011 track “The Zone”: “Well girl let’s go, walk your broken heart through that door / Sit yo sexy ass on that couch / Wipe that lipstick off of your mouth.”