From New Scientist‘s Feedback column:
Jerry points to a sign on a door at London’s Paddington train station with a yellow and black warning triangle and exclamation mark next to the legend “Low Voltage”. He also cites the Hilton hotel in Northampton, UK, which has a small fish pond with a sign cautioning: “Danger! Shallow Water”. Meanwhile, many TV programmes and DVDs warn that they contain “Mild Language”.
“Well, golly gosh!” says Jerry. He adds, more soberly: “As with anything that seems to defy common sense, I suspect that lawyers are involved somewhere.”