phrase heard in That 70's Show- "open for business". Period-appropriate?
I'm a great fan of That 70's Show and have been rewatching Season 1. In that season, the phrase "Open for business", as in sexual availability, is used once to refer to Donna being on the pill, and another time to refer to Stella (one of Midge's friends) being a cougar. Was this phrase used in the 70s, or is it an anachronism from the 90s? And where does it come from? (I know That 70's Show isn't 100% accurate)