I found basically the same math joke in two different youtube clips. It would be interesting if there were more examples. The first is from Abbot and Costello. The second looks to be from a movie called Ma and Pa Kettle. I'm not sure which clip was first. I like Ma and Pa Kettle slightly better, only because I like to hear Ma Kettle say, "I'm surprised at yer learnin'". 075 students I want an explanation of the mistake.