The first record to contain the word "rockabilly" in a song title was issued in November 1956 "Rock a Billy Gal"; although, Johnny and Dorsey Burnette recorded "Rock Billy Boogie" for the Coral label on July 4, 1956. The song had been written and performed much earlier, and refer to the birth of Johnny's son Rocky and Dorsey's son Billy, who were born around the same time in 1953, and were firstborns for each of the brothers. The song was part of their repertoire in 1956 when they were living in New York City and performing with Gene Vincent. It's easy to understand how the New York audience might have thought the Burnettes were singing "Rockabilly Boogie," but they never would, because the term "hillbilly" was derogatory and would never have been used by the artists themselves. Rocky Burnette, who later would become a rockabilly artist himself, has stated on his website that the term "rockabilly" derives from that song. It's also interesting that this song has been covered by hundreds of artists in the years since, and it is always called "Rockabilly Boogie".