I stumbled on an article that was published earlier this year from Forbes where you can test your mental sharpness.  I'm a pretty smart guy, and I thought this would be pretty easy.  After the first question, I was already puzzled.  I actually could feel my brain working.  Take the test and see how these seemingly simple questions can challenge you.

Here are a few of the questions:

1. Johnny’s mother had three children. The first child was named April. The second child was named May. What was the third child’s name?

2. A clerk at a butcher shop stands five feet ten inches tall and wears size 13 sneakers. What does he weigh?

3. Before Mt. Everest was discovered, what was the highest mountain in the world?

 

The answers are as follows:  1.  The other kid's name is Johnny, duh.  2.  A butcher weighs meat.  3.  Mount Everest was the highest mountain, it just wasn't discovered.

These questions play on how your brain thinks and exposes the fact that your brain can come up with conclusions too quickly, out of predictability.  Read more about the article at forbes, and see the other 7 questions.

By the way, I did get most of them right, but I couldn't figure out number 9.