格拉斯哥的勞裡教授在門上貼了這樣一個通知：「勞裡教授今天不見他的班級。」

　　一個學生讀了通知後，擦掉了字母「c」(lass：姑娘)。

　　後來勞裡教授來了，也想開開玩笑，他擦掉了字母「l」(ass：笨驢)。

Class and Ass

Professor Laurie of Glasgow put his notice on his door: "Professor Laurie will not meet his classes today."

A student, after reading the notice, rubbed out the "c".

Later Professor Laurie came along, and entering into the spirit of the joke, rubbed out the "l".