Usually groups of Men that like to dress up together in tight leather and ride around on motorcycles at the weekend. Often found at lunch time in country pubs with their leathers half off with tight white vests.
They also like to compare each others tight leathers, and rank is judged on whose leathers are the most expensive.
They also like to compare each others "helmets" by size and colour.
They are also often found complaining about drivers of automobiles, but will then quite happily cut up the inside of you on the motorway and complain when someone on a motorbike gets hurt because it was never their fault.