OK, I think I get the joke—"Earwig O" is supposed to sound like "Here We Go"—but I don't know of any song by that name. Is it a song known only in Britain? Sung at football games maybe? "Here we go" is heard at American sports games, but only as a chant, not a song.

Or is EARWIG O only a poem, not meant to be sung?

I think it would get a little tiresome hearing a poet read aloud all those repetitions of "Earwig O" if there were no tune to go with it.