Can you teach a computer to understand a sarcastic Tweet? Marketers, diplomats, the FBI, and others hope so. The explosion of social media has jump started a field known as sentiment analysis. The goal? To sift through the avalanche of Facebook posts, blogs and Tweets to glean how we feel about a new product, anticipate an uprising, or catch a criminal. And while humans have been trying to teach computers to understand language for decades, social media's penchant for slang, acronyms and a casual disregard for grammar are especially difficult. We explore the challenge of mining ones and zeros for feelings.