“One of my students wrote a story about a nun who got a piece of dental floss stuck between her lower left molars, and who couldn’t get it out all day long. I thought that was wonderful. The story dealt with issues a lot more important than dental floss, but what kept readers going was anxiety about when the dental floss would finally be removed. Nobody could read that story without fishing around in his mouth with a finger. Now, there’s an admirable practical joke for you.”