The British Medical Journal published an article titled "Sword swallowing and its side effects". And, guess what the researchers found? Swallowing swords is dangerous! Well, duh. (h/t: BoingBoing)
For example, one swallower lacerated his pharynx when trying to swallow a curved sabre, a second lacerated his oesophagus and developed pleurisy after being distracted by a misbehaving macaw on his shoulder, and a belly dancer suffered a major haemorrhage when a bystander pushed dollar bills into her belt causing three blades in her oesophagus to scissor.