http://tinyurl.com/5bpkf

Camco Campsite Occupied Sign

Code: 14-8313
Price:$14.19

Shipping Weight: 1.00 pounds
Avoid embarrassment by saving your space with this highly visible sign.
Priced each.

I have no interest or association with this company.. but thought it
was a novel Idea to solve a uncomfortable issue which isn't worth
$15+shipping..  I think I may make my own though..