twelve o'clock
Sister Bert sat down on the floor twice -- it was most amusing . A terrible thing happened just as the clock struck twelve . All my clothes turned into rags , and I just RAN out of the room , I was so frightened . Then I remembered what my Fairy Godmother had said about leaving before twelve o'clock . I suppose she knew what would happen if I did n't . I 'm afraid I left a glass slipper behind -- I hope she wo n't mind about it . Well , I 've had a lovely time .