ZUN ZUN ZUN ZUN DOKO KIYOSHI

zundoko.rb

module ZunDoko
  Z = 'ズン'
  D = 'ドコ'
  TARGET = [Z, Z, Z, Z, D]

  def self.kiyoshi(arr=[])
    arr.shift if arr.size > 4

    arr << [Z, D].sample
    return "#{arr.join("\s")} #{'キ・ヨ・シ！'}" if arr == TARGET

    kiyoshi(arr)
  end
end

ZunDoko.kiyoshi