What is the greaser rule besides "stick together"?It is found in Chapter 2.

In chapter two of The Outsiders, Pony, Johnny and Dally
have gone to the drive-in. They meet Cherry and Marcia, and Pony and Johnny are smitten
by the two girls. Dally, on the other hand, runs his mouth and shows how tough he is.
Cherry is not impressed and says so. Dally keeps bothering the two girls, and Johnny
speaks up and tells Dally to stop. Everyone is shocked that Johnny would stand up to
Dally; he idolized Dally. After Dally leaves, Cherry invites Pony and Johnny to sit with
them and makes a remark about how bad Dally is, but Johnny defends
him:

"Dally's
okay," Johnny said defensively and I nodded. You take up for your buddies, no matter
what they do. When you're a gang, you stick up for the members. If you don't stick up
for them, stick together, make like brothers, it isn't a gang anymore. It's a pack. A
snarling, distrustful, bickering pack like the Socs in their social clubs or the street
gangs in New York or the wolves in the timber. "He's tough, but he's a cool old
guy."

Pony is trying to
explain that in a gang you always stick together and have each other's backs no matter
what. Little did Pony know that this was the night that would change everything in
Pony's and Johnny's lives. The rule the Greasers had would be put to the ultimate
test.