What evidence does Holden give us that the other boys at Pencey Prep actually liked him and that he was in a cool group?

Oh, dude, Holden Caulfield from "The Catcher in the Rye" thinks he's all that, doesn't he? He mentions that the other boys at Pencey Prep would sometimes ask him to go to the movies or grab a burger, so I guess that's his proof that he was part of the cool kids club. But hey, who needs validation from others when you're as cool as Holden, right?