If no one buys a ticket to a movie, does the movie still play?
Why isn't sour cream really sour?
Why isn’t the Q or the Z included on the phone
Why is Bra singular and Panties plural?
What are those little things on the end of your shoelaces called?
Do fish ever get thirsty?
If there were a knowledge contest, would the female winner be called Miss Informed?
If you stick on stickers on non-stick pans, would they stick on?
Why don't ducks duck when you shoot at them?
On a hamburger bun, why is the top bun always bigger than the bottom one?
Why does breaking a mirror mean seven years of bad luck when seven is a lucky number??
If I think, and therefore I am, am I just a thought?
If ignorance is bliss, why aren’t more people happy?
Why do the numbers on the phone go one way, but the numbers on the calculator go the other way?
Why do we tie shoes to the back of a car for newly weds?
Is it possible to do stand-up comedy sitting down?

For more:

http://www.crazythoughts.com/

A couple of mine:

Why is the March of Dimes held in January?

If this is the 21st Century, then why hasn't the movie studio 20th Century-Fox changed its name yet?

And speaking of knowledge contests…

Would MissInformation win that knowledge contest?

My favourite:

If you mated a bull dog and a shitsu, would it be called a bullshit?

ROTFLMAO!

I've always wondered why we don't sneeze in our sleep.

Some of these questions are answered at the Straight Dope web site.

Crazydon's 20th Century Fox question intrigues me.  I know that the company moved away from the name in some instances (FOX television, for instance), but they seem wedded to the name

Here's a point to ponder, why is a diamond a girl's best friend but a man's best friend is a dog?