What do greasers do that make people think of them as delinquents ?

The Greasers slick their hair back and wear similar clothes. They steal things not because they need them rather than to show people they rebel against laws and societal rules. 

The greasers have a terrible reputation for many reasons. One of the reasons why is because they dress like hooligans. They do lots of criminal activities like steal small things like food, smoke “a weed”, and participate in rumbles. Even though they do evil stuff like this they are good people. They look out for each other and steal out of necessity