Complex sentence: The song was first conceived, Mellencamp claims, in his shower and the first lines created were those of the chorus written by Mellencamp, he then said the lines to Green and they finished the song very quickly.
Split into simpler sentences: The song was first conceived, Mellencamp claims, in his shower and the first lines created were those of the chorus written by Mellencamp. He then repeated the lines to Green and they finished the song very quickly.