Well actually - don't do this anywhere. I was reading aus.bicycle in this thread there was a link to the Naval Safety centre which has a Photo of the Week of safety breaches.
The photos are astounding - the tractor that's crashed through the ice, the temporary light made of a light fitting alligator clipped onto live wires - people holding down loads on the back of trailers. It's amazing the things people will do with ladders.
As alexone of the posters found maybe what you shouldn't do is look at this site at work because you keep on looking at just one more.