Jim Grieve adds: "Yes, 'Grroosss' is the actual word (taken straight off the lyric sheet). Jeff Lynne says it's just a word he made up. Although Mack (the German engineer who worked on this album) noted that it sounded kind of like the German word for 'good morning' ('guten Morgen'). Most folks think it sounds like they're singing 'Bruce'. For that reason, when the song is performed these days, Jeff will sing 'Bruce' instead.