The Mad Gasser of Mattoon is the name ascribed to the person or people believed to be responsible for a series of apparent gas attacks that occurred in Mattoon, Illinois, during the mid-1940s, but has subsequently been dismissed as an episode of Mass Hysteria. 

So, imagine someone sneaking from house to house in the dead of night with a tank of poisonous gas, slipping the hose into your window, and turning it on. Pretty damn freaky, huh? But is it freaky enough to cause mass hysteria? And what is mass hysteria anyway? Joe and Jerry take a deep dive into that in this episode of Acceptably Real.