Explore the fascinating intersection of fear and pleasure in this Royal Institution lecture. Delve into the psychology behind thrill-seeking behavior, examining why humans actively seek out frightening experiences like horror movies and rollercoasters. Learn about the 'thrill-seeking gene', techniques for optimizing rides to engineer fear, and the underlying reasons we find being scared enjoyable. Discover how researchers measure and analyze emotional responses to thrilling experiences, including facial coding and physiological indicators. Gain insights into the science of roller coaster design, the role of the vestibular system in experiencing thrills, and cutting-edge experiments involving adaptive rides and virtual reality. Uncover the complex relationship between fear, pleasure, and human psychology in this comprehensive exploration of why we like being scared.