Psychobilly is a genre of rock music that mixes elements of punk rock, rockabilly, and other genres. It is often characterized by lyrical references to science fiction, horror and exploitation films, violence, lurid sexuality, and other topics generally considered taboo, though often presented in a comedic or tongue-in-cheek fashion. Psychobilly music is often played with an upright double bass instead of the electric bass more common in modern rock music. Psychobilly gained underground popularity in Europe beginning in the early 1980s, but remained largely unknown in the United States until the late 1990s. Since then the success of several notable psychobilly bands has led to its mainstream popularity and attracted international attention to the genre.