Al Jefferson is a 6'10" human. He plays center for the Utah Jazz. And he happens to have a 10 ft. by 12 ft. bed. Do you know how many of me can fit into that Hulk of a bed. I am about 5'8", which is the average height of human beings (if you disagree, I will fight you to the death) and about 20 inches wide (yes, I actually measured) laying down with my hands by my side. That bed will fit six of me horizontally and two vertically, with inches of leg room.
If you still don't believe me, look at the picture below. That's 6'1" Mo Williams, he looks like he just climbed up the beanstalk and crawled on to the Giant's bed. Unbelievable!
Oh, and if you are interested, here's the actual receipt