What Is A White Elephant Gift?

What exactly is the White Elephant gift?  According to the vast interwebs it's a gift that is often times hard to get rid of as well as a burden to upkeep.  Nowadays it is usually a funny gift that there is no real practical use for.  

The real question is... How much junk can I get rid of from my house at one time?  I accept this challenge and cannot wait for the White Elephant gift exchange tomorrow!

Tell us about your white elephant gifts.  Have you ever gotten a horrible gift you thought was a white elephant but wasn't?