people?

that quiet girl in your math class might be the best singer ever, but only the bar of soap knows that
that boy that smokes pot might be the future CEO of Apple (Steve Jobs smoked pot)

that nerdy kid might be in stocks, and currently has $35,123 in his bank account
that "tough guy" might go home everyday and watch Gossip Girl on netflix
that pretty popular girl might be anorexic
that kid who you think has it all might be contemplating suicide
that teacher that you hate might spend hours and hours preparing each lesson  
that chubby girl might be an amazing actress and be famous one day, maybe even the next "fat Amy"
that weird girl in creative writing might be the next New York Times best seller

no matter how much you think you know people, you don't.