Also found in: Wikipedia.
During the Dark Ages before computerized directory assistance, callers who didn't know a phone number dialed the operator and asked to be connected to “information.” The information operator would then supply the number, and at no charge. “Information” with “please” added in a more polite era, was adopted as the title of a very popular radio quiz show in which a panel of experts tried to answer questions submitted by listeners. The phrase then became widely used as a preamble to any sort of question. The radio program was satirized by another quiz show whose title “It Pays to Be Ignorant” also became a brief fad in everyday speech.
See also: please