According to Wikipedia… “Silverman was inspired by the ad-lib “doo-be-doo-be-doo” he heard at the end of Frank Sinatra’s interpretation of Bert Kaempfert’s song “Strangers in the Night” on the way out to one of their meetings, and decided to rename the dog “Scooby-Doo” and re-rechristen the show Scooby-Doo, Where Are You”