#xyzzyで這いよれ!ニャル子さんのアレ

gistfile1.lisp

(let ((i 0))
  (unless (get 'mode-line-format 'save)
    (setf (get 'mode-line-format 'save) mode-line-format))
  (defun u-nya- ()
    (let ((pattern '("(」・ω・)」うー！"
                     "(／・ω・)／にゃー！"
                     "(」・ω・)」うー！"
                     "(／・ω・)／にゃー！"
                     "(」・ω・)」うー！"
                     "(／・ω・)／にゃー！"
                     "Let's＼(・ω・)／にゃー！")
                   ))
      (setq mode-line-format (concat (get 'mode-line-format 'save) " " (nth i pattern)))
      (setq i (rem (1+ i) (length pattern)))))
  (add-hook '*post-command-hook* 'u-nya-))

;; お片づけ
(progn
  (delete-hook '*post-command-hook* 'u-nya-)
  (setf mode-line-format (get 'mode-line-format 'save)))