Can't believe no one has suggested ' Rad ' or 'Radical'? Or was it just the mags that used it?
Favourites from my neck of Yorkshire were.....
Spanner-a take on spaz or spakker
Ger-a-barra, suggesting that one should exchange that shonky Claud Butler for a wheelbarrow- ultimate insult when unvieling a new bike.
Dimps- a remnant of cigerette
Keggy- riding piggy back
Laykin art- playing (last two of Nordic origin)
Wangers and kecks- trousers and undies
Thrappers- soiled underwear, usually used after crash or fright 'shatty thrappers'
Andy Crane- an idiot or twat
Stinky fingers- mam and dad going out, house to yourself with your new girlfriend
Tapper, kadger- scrounger
Joey- see Spanner
Tar(t)- sneek in a clipped T' after getting served by Billy's mum in the chippy.
Burnabarht- riding around
I'm sure mrs will come to me as the day wears on. Sadly many are not printable.