In this episode of 'Stuff You Should Know,' hosts Josh and Chuck explore the haunting tale of the Madd Gasser of Mattoon, Illinois, which gripped the small town during the anxieties of World War II. They recount the bizarre gas attacks of 1944 that left residents paralyzed after inhaling a sickening odor, and the ensuing public hysteria amplified by local media coverage. The narrative dives into the chaotic police response, community reactions, and the subsequent analysis that deemed the incident a classic case of mass hysteria, while also considering alternative theories regarding the possible identity of the Gasser.