A royal flush in poker consists of the ace, king, queen, jack and ten, all in the same suit. Our magic begins by having the spectator choose one of the cards in any of the four royal flushes. This choice could be by random draw or the spectator can merely think of one of the 20 cards. In either case he does not inform the magician of his choice but will write it on a slip of paper for future reference.
"Magic in Six Dimensions,"
Word Ways: Vol. 43
, Article 12.
Available at: http://digitalcommons.butler.edu/wordways/vol43/iss4/12