Americans eat three pounds of peanut butter per person every year, enough to coat the floor of the Grand Canyon! (I wonder how they know it is enough to coat the canyon floor?)
Astronauts cannot burp in space because gravity is too low; liquids do not separate from gasses in the stomach, so belching is impossible. (A good reason to live in space!)
'Bookkeeper' is the only word in the English language with three consecutive double letters.
Your screams cannot be heard in space because there is no air to carry the vibration of your voice. (There's another good reason that I suspect mr. kenju would like us to live in space.)
When glass breaks, the cracks move at speeds of up to 3,000 miles per hour.
The focusing muscles of the eye move about 100,000 times a day. To give the leg muscles the same exercise would involve walking 50 miles each day!