When asked about their online privacy, most people think they got nothing to hide. With my talk, I want to show that this is probably not true. To do this, I'll show a series of experiments that demonstrate how easy it is to learn interesting and sometimes very private things about people by analyzing the data trails they leave behind. I will discuss the risk of permanent de-anonymization of user data and propose technical as well as societal strategies that we can employ to protect our privacy.