Gordon Bennett! is an expression or exclamation common in some parts of the United Kingdom that shows (often exasperated) surprise, annoyance, or shock.
According to Bill Bryson, James Gordon Bennett, a newspaper baron, liked to announce his arrival in a restaurant by yanking the tablecloths from all the tables he passed. He would then hand the manager a wad of cash with which to compensate his victims for their lost meals and spattered attire. Though long forgotten in his native land, Bennett and his exploits were once world famous, and indeed his name lives on in England in the cry, "Gordon Bennett!"
You can imagine my surprise when I found this plaque in Germany.