CPod took a religion course at BYU with a professor who surprised them from time to time with what he called "quizzies": brutal pop quizzes of 10 questions each. The class was small, and so the students developed a level of familiarity with one another and the professor, and all felt comfortable joking around to a certain degree.
One day, the professor, of course, sprung a "quizzie" on the class. After it was over, and they had traded papers to grade them, one young, innocent freshman girl said to the professor and class at large, "Boy! If these are your quizzies, I'd hate to see your testies!"
Oh, yes. She did. CPod says it took a minute for the awkward silence to finally degenerate into honest-to-goodness laughter, but that poor girl was never quite the same again.