That's actually a line in the song, though.>HEYHEY! 人間賛歌 愛逃げ 人間不安か?
Or, in romaji:>HEYHEY! ningen sanka ai nige ningen fuan ka ?
Which is the line they translated and subtitled.
It's wordplay. In one part he's saying "sanka" and "fuan ka" and in the other part he's "sucker" and "fucker". Doesn't make the subtitles correct, though, since the part in the Death Note version is "sucker" and "fucker".