Rockers, leather boys, Ton-up boys, and possibly café racers are members of a biker subculture that originated in the United Kingdom during the 1950s. It was mainly centred on British café racer motorcycles and rock 'n' roll music. By 1965, the term greaser had also been introduced to the UK and, since then, the terms greaser and rocker have become synonymous within the British Isles although used differently in North America and elsewhere. Rockers were also derisively known as Coffee Bar Cowboys. Their Japanese counterpart was called the Kaminari-Zoku (Thunder Tribe/Clan/Group, or Thunderers).