Go to any restaurant in Massachusetts. In the bathroom there's a little sign that says, "Employees must wash hands." I think sometimes it says that it's a state law or something like that.
I don't think that's good enough. I think it should say:
"Employees as well as patrons must wash hands."
But perhaps that's a little too pissy. You might want to tone it down a notch and say:
"Employees as well as patrons are strongly encouraged, with extreme prejudice, to wash hands."
Or even gentler...
"Kindly wash your hands so that when you shake other people's hands and prepare their food, your hands are not so penisy, and you do not transfer to innocents whatever horrid disease you carry."
I know. There is the whole other subject of people wiping their asses and not washing their hands afterward. I can't even bare to discuss it.