Pony does not want pity because it means that people who barely know him feel superior to him. He explains that some people consider the greasers inferior and in need of charity, when he actually likes who he is. Pony takes pride in being a greaser, and does not want anyone to pity him.
Did they hate us now? I hoped they hated us, that they weren't full of that pity-the-victims-of-environment junk the social workers kept handing Curly Shepard every time he got sent off to reform school. I'd rather have anybody's hate than their pity. (ch 11, p. 163)
Pony is fully aware that he and his friends are usually ending up on the wrong side of society, and prefers that others would just leave the greasers alone, because they do not go looking for trouble. They try to keep to themselves, and do not want to be pitied as victims. If they are going to be misunderstood, it is better to be hated, because they are not seen as inferior.
In Chapter 11, Ponyboy says he hopes the Socs hate him and his fellow greasers rather than pitying them. He says, "I hoped they hated us, that they weren't full of that pity-the-victims-of-environment junk the social workers kept handing Curly Shepard every time he got sent off to reform school." If the Socs hate Ponyboy and his family and friends, he thinks it means the Socs consider them worthy rivals worthy of hate. If they pity him, that would mean they consider him lesser in some way.
Ponyboy already feels he, his brothers, and the rest of the greasers do not measure up to the Socs because the greasers are from the "wrong" side of town—the poorer side where people don't usually have the opportunity to go to college. As Ponyboy says in Chapter 11:
We live in kind of a lousy neighborhood and our house isn't real great. It's run-down looking and everything, and the inside's kind of poor-looking, too, even though for a bunch of boys we do a pretty good job of house-cleaning.
Although Ponyboy and his brothers are poor, they do everything they can to protect their dignity. They try to keep their house clean, and Darry pushes Ponyboy to achieve what he can. Fighting the Socs is another way the Greasers try to maintain their dignity. If others pity them, Ponyboy would lose face and start to feel that his dignity was slipping. In addition, if people such as social workers pity them, it implies that something is wrong with them and the way they live. Ponyboy does not feel that the way in which he, his family, and his friends live is wrong.
In Chapter 11 of S.E. Hinton's novel The Outsiders, Ponyboy is reflecting on the distinctions between the Greasers and the Socs and the air of superiority the latter perpetually feel regarding the former. Following Johnny's killing of Bob Sheldon, Ponyboy ponders the attitudes of the Socs towards the Greasers' "killing" of one of their friends:
"Did they hate us now? I hoped they hated us, that they weren't full of that pity-the-victims-of-environment junk the social workers kept handing Curly Shepard every time he got sent off to reform school. I'd rather have anybody's hate than their pity."
Ponyboy understands hatred; the two sides of this divide hate each other, which serves as an equalizer of sorts. Pity, however, suggests that the Socs, whose parents occupy far higher rungs of the socioeconomic ladder, look down upon the Greasers and consider themselves morally superior to the kids from 'the other side of the tracks.' Pity suggests weakness, and the Greasers would never condone demonstrations of pity directed towards them.