Greaser
Guys: someone who dresses in rockabilly/psychobilly clothes, always has a comb in their back pocket, styles their hair in a pompadour or slicked up and back, wears a little bit of tighter pants then anyone else, sometimes wears white or black wife beater, wears leather jackets or jean jackets, black converse, cigarette held behind ear, styles their hair in petroleum jelly or pomade. 

Girls: Styles their hair in a pompadour sometimes which is let down or tied the rest back in a pony tail, sometimes short bangs that curl like sausages (haha), polka dots, high heels, tight pants, colourful fashion shirts, comb in back pocket or purse, cigarette behind ear, converse, styles their with pomade and hair spray, a lot of jewelry, red lipstick, etc.
The outsiders, Grease I, Grease II, Cry Baby...... (there are still some greasers around besides from the 1930-1960s. be a fucking greaser bitches)