Wiktionary
n. A message delivered by an artist in a musical form.
Wikipedia
A singing telegram is a message that is delivered by an artist in a musical form. Singing telegrams are historically linked to normal telegrams, but tend to be humorous. Sometimes the artist is in costume or formal clothing. Singing telegrams are often given as a gift.
Western Union, the American telegraph company began offering singing telegram services in 1933. On July 28, 1933, a fan sent Hollywood singing star Rudy Vallee a birthday greeting by telegram. George P. Oslin (1899–1996), the Western Union public relations director, decided this would be a good opportunity to make telegrams, which had been associated with deaths and other tragic news, into something more popular. He asked a Western Union operator, Lucille Lipps, to sing the message over the telephone, and this became the first singing telegram. While Oslin created the singing telegram because he thought "that messages should be fun," he recalled that he "was angrily informed I was making a laughingstock of the company."
As relatively few telegram recipients had telephones, most telegrams, including singing telegrams, were first delivered in person. The popularization of the telephone in the 1960s reduced telegrams in general. By 1972, Western Union was receiving a small number of requests for singing telegrams and was seeking regulatory approval on a state-by-state basis to eliminate the offering. Western Union suspended its singing telegram service in 1974, but independent singing telegram companies, specializing in often costumed personal delivery of gift messages, have kept up the tradition.