 According to the book "Billy Gibbon: Rock & Roll Gearhead", ZZ Top  was hanging around the set and was asked to be the town band. During  one take, the camera broke. While waiting for the camera to be  repaired, Micheal J. Fox asked if they would play "Hey Good Lookin"  which they did. Afterwards, more requests were played. Two hours  later, someone inquired if the camera had been repaired. The  director replied that it had been fixed for quite a while, he just  didnt want to stop the party that had evolved.