Flight attendants have witnessed many repulsive misuses of the tray table, from parents changing dirty diapers to kids sticking their boogers underneath. Research confirms that the handy tray table is a petri dish for all kinds of health hazards, including the superbug Methicillin-resistant Staphylococcus Aureus (MRSA), which is often fatal once contracted. It kills an estimated 20,000 Americans annually. In 2007, University of Arizona researcher Jonathan Sexton tested tray tables from three major airliners, and an alarming 60 percent tested positive for the superbug. That's quite a revelation considering only 11 percent of his samples from the New York subway found traces of the bug.