[I made up the following all by myself. Though it doesn't take a genious to come up with this idea, I haven't seen it anywhere else. Perhaps this better belongs to rec.puzzles, but hey, you're the judge.] Instructions: Get one of your ten-fingered touch-typist friends to type the following, and determine how long it takes till he/she begins to see that something's weird. (Yet another good use for grep and /usr/dict/words.) i join my union. i only jump on you. in my opinion, you look plump. pin holly on johnny. kill my unholy puppy.
(From the "Rest" of RHF)