The Sardonic Smile
I knew about the cynical/vengeful expression of a sardonic smile but I had no idea about it as a medical term. In medicine, it is defined as a smile-like facial expression induced by involuntary muscle spasms most often caused by toxins released by tetanus bacteria. However in folklore, the sardonic smile has a much more interesting past. It might have to do with the ingestion of the sardonion plant from Sardinia which cause muscle spasms, laughter and death.