Basically, there is this big purple fly who bites smurfs on the ass, giving them the Smurf Disease. The infected smurfs turn purple and grit their teeth and say "GNAP! GNAP!" Now the sick smurfs are driven by only one purpose; to bite other smurfs on the ass and spread the disease. Which they do. Holy s**t. This made me crap my pants. Who green-lighted this episode? This just about did me in as an eight-year-old.