twelve o'clock at night
Thereafter he kept his temper . `` I 've heard it said that a mule would n't kick after twelve o'clock , '' said Chunky . `` Guess it was n't true . '' `` Perhaps it is after twelve o'clock at night that was meant , '' suggested Tad . `` Mules are asleep then , are n't they ? '' `` Supposed to be , I guess . '' `` Then that 's it , '' answered the fat boy somewhat enigmatically .