Seen on the office door of one of the faculty:
(click to read.)
One of the biggest hazards of doing science in the field is tampering and theft by random passersby. It never helps to explain anything in the hopes that people will just nod along and leave things alone. Trickery and camouflage tend to work better. When I was in grad school helping a fellow student do some research with shorebirds, they had a box of tracking equipment that had to just sit out in the middle of an island. It was surrounded by a useless but official looking fence and plastered with "Warning: High Voltage" signs. Seemed to work pretty well.
And perhaps humor works well too. ;) The above sign, which is probably also out in the field attached to some electronic equipment too heavy to steal, reminds me of the birdwatcher's box.