Why do you carry around a Korean banknote in your wallet?

One of my teachers once felt I was being overshadowing in my contributions to class discussion in an interdisciplinary course on Literature, Biology, and Sociology so he gave me five Korean dollars not to talk. Every time I spoke up to make a divisive opposing viewpoint he took the money away from me, but I didn't really care...

XKCD

same principle, I made a point to save the last one before class ended as a lucky reminder of the value of shutting up occasionally.