In the Outsiders, why is Dally so inconsiderate to the girls at the movies? How does this acknowledge his character as a friend to both Johnny and Ponyboy?

As much as anything Dally needs to cement his role as a greaser and a "bad" one at that. He needs not to be seen as weak and cannot be nice to the girls because he might be seen as less than serious in his role in the gang. Dally is especially conscious of being "good" to Johnny because he knows Johnny has had a rough life. Dally wants to be seen as the "bad boy" and must maintain that persona regardless of what he feels for other people as individuals.