http://en.wikipedia.org/wiki/List_of_US_presidents
If you made it all the way to Washington, you can keep masturbating an extra 40 strokes while you check over the list and see if you missed anyone. Otherwise, keep your hands to yourself while you check.
If you skipped even one, put your balls in the ice bowl and hold them there wile you give yourself 20 ruler smacks on the shaft and 5 right on the head.
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