As non-intuitive puzzles go I think the hat guessing game (http://www.relisoft.com/science/hats.html http://www.relisoft.com/science/hats.html) takes the cake.

As non-intuitive puzzles go I think the hat guessing game (http://www.relisoft.com/science/hats.html http://www.relisoft.com/science/hats.html) takes the cake. I still remember a dailywtf thread where 19 pages worth of people claim that the correct solution is completely bogus (http://thedailywtf.com/Comments/Riddle-Me-An-Interview.aspx http://thedailywtf.com/Comments/Riddle-Me-An-Interview.aspx).