Quotation Marks

Check out the use of quotation marks on the sign above.

I've long wanted to collect examples of the great variety of uses quotation marks are put to in public signs. Please submit examples. My hope is that as we collect examples, patterns will emerge and we can begin to understand why they are used to mark something other than the fact that someone is being quoted or that the enclosed word(s) are being mentioned, not used. Here's an example of such a deviant use of quotation marks that only began to make sense to me once I had others to compare it to:

A "No Smoking" sign in a restaurant. I feel like this is like "Pay Before Pumping" signs I've seen at gas stations. In these cases, I feel like the quotation marks are letting you know that someone is ordering you to do (or not do) something. They're "command marks", one could say.

So what are the quotation marks in the sign above doing?