The bakery and coffee shop in the picture is not offering X-rated entertainment, but it is intentionally playing with your mind with that round blue sign that actually means "edible" in Swiss German; elsewhere a German sign would say "essbar." The slogan "Frisch von Gestern" tells the rest of the tale; they specialize in unsold pastries that are "Fresh from Yesterday."
On my first trip to Basel a few years ago, I lost my illusion that it's a German-speaking city. While I can usually get around in German and get what I need, in Basel I found that the answers I got to my carefully-phrased questions sounded almost as if they were in another language—and they were.
Swiss German, or Schweitzerdeutsch, or any of several regional spellings, is recognizably German, but shows both remnants of ancient and regional dialects and borrowing from neighbor languages such as Italian and French ("Merci vilmal" for "Danke vielmals" when you want to say "Thanks a lot").
During my three weeks in Basel this year, I learned quite a few important Swiss German words almost all relating to food, starting with Schoggi (chocolate).