Night prowls are a condition similar to night hysterics in which a sleepwalker commits heinous acts in the middle of the night. It is a side effect of the Kern Pharmaceuticals erectile dysfunction drug Peniscillin. Peniscillin went on the market in 1991, and for the next three and a half years, men who took the drug would climb out of their house in the middle of the night, join each other and go prowling.
In an interview on The Best Show on WFMU on December 21, 2004, Kern Pharmaceuticals CEO Maurice Kern stressed that the night prowlers were only "crazed", and were not so far gone as to become "rabid". Kern also dismissed rumors that the patients had become zombies, emphasizing the distinction between "zombies" and "zumbies".
The night prowl crisis was easily contained by apprehending and quarantining the zumbies for several months. It is suspected that the patients were being shot in the head before Kern Pharmaceuticals realised such drastic measures were not necessary.
Keith Garfinkle once claimed to have the condition in order to get out of the Marines because drill sargeants were yelling at him to do push-ups. His parents refused to back his claim because it was false.