There's a lot of artwork of Retsuko taking Isabelle to karaoke and singing death metal, but what about the other side of it? Isabelle taking Retsuko to the arcade to play Doom? I bet that would be just as crazy.
I get the feeling that whatever karaoke machine there is in Animal Crossing doesn't have anything heavier than Van Halen or Guns N' Roses on it (and if we're just talking about women, nothing heavier than Heart or Jagged Little Pill era Alanis Morissette). From what little I know about Retsuko, her reaction would essentially be "I need something angrier and heavier."