Dubstep

My:
object Wub {
def songDecoder(song: String): String = song.split("WUB").toList.filter(x=>x!="").mkString(" ")
}

Other:
object Wub {

  def songDecoder(song: String): String =
    song.replaceAll("(WUB)+", " ").trim
}

object Wub {
  def songDecoder(song: String): String = song.split("WUB").filter(!_.isEmpty).mkString(" ")
}