"Don't pet the wildlife". This seems like a no-brainer to the average Wyomingite, but for some strange reason, a large percentage of our annual tourist population just doesn't get it.
If you visit Yellowstone National Park now, you'll find feeding bears solidly in the "don't" column. But, there was an era many years ago when people were not only allowed to feed bears in Yellowstone, the practice was sort of encouraged.