The Big Bopper is a deceased man buried at the Springfield Cemetery. His gravestone reads "Gooooodbye, baby!" with a statue of himself on the phone. He lived from 1930–1959.
After finding Edgar Neubauer's grave, Bart and Lisa learned that Mayor Sideshow Bob had stuffed his ballot with "votes" cast from deceased people and animals buried at the Springfield Cemetery and Springfield Pet Cemetery, respectively, among them The Big Bopper.
"The Big Bopper" was the stage name of pioneering rocker J. P. Richardson, best known for the song Chantilly Lace. He died on February 3, 1959, in the same plane crash that also killed Buddy Holly and Richie Valens.
Chantilly Lace represents a telephone conversation between The Big Bopper and his girlfriend (of which we only hear his half) and the opening line is "Hellooooooooo, baaaby!"; hence the statue and the epitaph.