Psychobilly is genre of music, usually described as mixture of fast, vicious rockabilly and punk.
It's 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 is generally played with an upright double bass instead of the electric bass more common in modern rock music.
The term "psychobilly" was first used by Wayne Kemp when he penned the Johnny Cash song "One Piece at a Time," a Top 10 hit in 1976, where he makes reference to a "psychobilly Cadillac", although this song has nothing musically to do with Psychobilly. It came into use as a genre a few years later, when the Cramps described their music as "psychobilly" and "rockabilly voodoo" on flyers advertising their upcoming shows. Although the Cramps rejected the idea of being a part of the psychobilly scene, they, along with artists such as Screamin' Jay Hawkins and the Stray Cats, are considered important precursors to psychobilly. Musically speaking, there are also antecedents in the garage rock scene of the 1960s and the pub rock scene of the 1970s.
The very first verifiable psychobilly band is considered to be The Meteors in south London in 1980. With one member being part of the rockabilly subculture, another being part of the punk subculture, and the last being a horror movie fan, their musical ideas overlapped to begin psychobilly as it exists today. The Meteors also invented the concept of psychobilly being a-political, by encouraging their shows to be a "politics-free" zone in order to avoid disputes among fans, as was becoming common in the punk rock scene of the time. The Meteors' second LP, Wrecking Crew. It is considered a classic and influential psychobilly album.
While the psychobilly of the early 1980s (the Meteors, the Sharks, Batmobile) was similar to punk or 1960s garage rock, with obvious rockabilly influences, the psychobilly of the later 1980s and 1990s (the Nekromantix, Demented Are Go, the Klingonz, Mad Sin, Asmodeus, Milwaukee Wildmen) had a different sound which was a bit harder.
The current psychobilly is closer to the American psychobilly sound (Tiger Army, The Spectres, The Knuckle Draggers, the Koffin Kats, Los Gatos Locos, the Barnyard Ballers, The Young Werewolves, The Beards and The Matadors).
Source: Wikipedia