  Class and Ass 班和笨驴

  Professor Laurie of Glasgow put his notice on his door: "Professor Laurie will not meet his classes today."
  格拉斯哥的劳里教授在门上贴了这样一个通知："劳里教授今天不见他的班级。"

  A student, after reading the notice, rubbed out the "c".
  一个学生读了通知后，擦掉了字母"c"(lass：姑娘)。

  Later Professor Laurie came along, and entering into the spirit of the joke, rubbed out the "l".
  后来劳里教授来了，也想开开玩笑，他擦掉了字母"l"(ass：笨驴)。