I was standing in a queue today and the 2 women behind me were discussing work. One said her job was health and safety and was to go around offices showing people how to use a shredder correctly. I could do that.
Rule 1. Don't put your hands in it.
Rule 2. Don't lean forward and trap your tie/necklace/hair in it.
Rule 3. Don't put the remainder of your sandwich in it.