Eric's Theory of New York City:
That, despite claiming over 8 million residents in a 322 square mile area, New York City ("NYC") is actually comprised of only 6 different companies and 25 people.  The Theory of New York City is evident:

• when traversing the sea of tens of thousands of city-dwellers and running into someone you know;
  
• when speaking to someone you've never met, completely outside both of your social realms, you discover by the fourth sentence that you have at least 2 mutual friends; or
  
• when you realize the majority of your Facebook friends don't actually exist.