http://www.geocities.com/RainForest/Wetlands/5380/arckat/operationmindfu
ck.html I guess this is a good site to kind of get the jist of what this is all about. I personally think this kind of psychological and mental discord is the best stuff ever, getting a kick out of other people's confusion over something so small and simple.
seeing how easily the mind cracks, it's a fascinating thing.
for example: print out 365 sheep cut them out and draw a number on each one, 1 through 365. Each day, send the first sheep to your unsuspecting victims house for 365 days and watch them go insane.