Try to not think about penguins

Thing to do when you're bored

Try to not think about penguins
(Amusement Potential: 1-5 minutes)
This is especially hard, because by trying too much, you remember what you were trying to avoid thinking of. If you try too little, you end up thinking about penguins anyway.

Link:
http://www.urban75.org/useless/bored.html