Sword swallowing is no illusion. Hannibal Hellmurto swallowed several different swords during his act in the March 2012 "Circus of Horrors" show in the U.K. before things went terribly wrong. His final trick was to swallow a neon sword, a feat so dangerous that most sword swallowers shy away.
A neon sword is basically a battery-powered neon light bulb, similar to the ones you see in the ceiling of most office buildings. The major concern with this trick is that if something does go wrong, you can end up with broken glass inside of your body. That isn't what happened to Hellmurto, though. Instead, he accidentally tore a 4-inch (10-centimeter) hole in his trachea [source: McQueeney]. Like Princess Tenko, Hellmurto finished his act before collapsing offstage.
The rupture occurred in a section of Hellmurto's windpipe that made it inoperable, so after doctors drained the blood that had pooled in his lungs, Hellmurto had to convalesce for five weeks until he healed completely. He couldn't eat or drink, and for the first couple of weeks he couldn't even speak. Twelve weeks later, he was back to training, and just nine months after his injury, he was back to performing [source: O'Connor].