"The Just-Testing User" is not even using a computer but wants to test your knowledge and, if possible, trip you up. The best technique for dealing with this species is by answering questions with "I don't know." They cannot deal with this straight capitulation. Most Just-Testing Users would love the chance to show your boss how useless you are or how little you know. They are thrilled when you give a wrong answer and will crow about it incessantly.
Caption by: Jeff Dray
Photo credit: ©iStockphoto.com/NickS