Decades before the Dr. Zizmor dog parody ads, Etti the Courtesy Cat was an actual public service rep on NYC subways, and went so far as having a book published (page scans available here).

Two things:

• I like how Etti’s white whiskers become black when cast against a white background.
• When did “PLEASE SORRY THANKS” go out of style?

Aside:

During my meta-hunt, it would appear this advertising copywriter plagiarised the PST slogan for a Ted Baker campaign in Australia. (It’s also apparently the name of a Telugu film.)