The Job Interview
A mathematician, an engineer, and a physicist are being interviewed for a job. In each case, the interview goes along famously until the last question is asked: "How much is one plus one?" Each of them suspects a trap and is hesitant to answer.
The mathematician thinks for a moment, and says "I'm not sure, but I think it converges". The physicist says, "I'm not sure, but I think it's on the order of one". The engineer gets up, closes the door to the office, and says "How much do you want it to be?"