Prior to the new self-aware wrestling product that is currently in vogue (worked-shoot angles, insider references, playing to the internet smarks), the biggest break of kayfabe occurred in 1987 when WWF superstars 'Hacksaw' Jim Duggan and The Iron Sheik were arrested and charged with narcotics posession while sharing a car between venues.
The story made the national media, and unlike today, when the wrestling establishment would regard any drug-related negative publicity as the major crime being committed by its employees, Vince McMahon and the wrestling fraternity were much more horrified that two wrestlers who were ostensibly feuding (The Iron Sheik being an Iranian sympathiser and Duggan being a plank-wielding patriotic goof) were caught together outside the ring, thus exposing the business of wrestling as a made-for-TV sham. Both men were immediately suspended by the WWF.