This question was inspired by a segment on Jimmy Kimmel last night where they ask random people in the street if they know a fact. My answer would have been "the earth revolves around the sun", it is the first fact that comes to mind that I'm almost 100% sure is the general consensus. Honestly, put on the spot it would be hard to think of facts even though most of us know thousands of facts. The tricky part is a lot of "facts" I know, like "there are 8 furlongs in a mile", I wouldn't be confident of when put on the spot and some "facts" I know I'm probably mistaken about.