According to Two-Bit, why don't the Socs fight fair in The Outsiders?

Two-Bit says the Socs do not fight fair because they gang up on a guy. 

When Johnny, Pony, and Two-Bit are at the movies with two Soc girls, Cherry and Soc, it is an usual experience for all of them.  It is not common for Socs and greasers to hang out together, but the girls have ditched their boyfriends for being drunk and they are being polite to the greasers. The girls find Pony and Two-Bit’s conversation about Dally and Tim Shepard interesting.  Two-Bit says that Shepard is looking for whoever slashed his tires, but there will be a fair fight.  Greasers fight fair, he says, but Socs do not. 

"A fair fight isn't rough," Two-Bit said. "Blades are rough. So are chains and heaters and pool sticks and rumbles. Skin fighting isn't rough. It blows off steam better than anything. There's nothing wrong with throwing a few punches. Socs are rough. They gang up on one or two, or they rumble each other with their social clubs. (Ch. 2) 

Basically, when two greasers have a problem, they fight.  The Socs gang up on one person as a group.  These are not fair odds.

The differences between Socs and greasers are many.  They are constantly feuding, with territory firmly drawn.  Cherry tries to explain to Pony that Socs are not all the same, and they have problems too.   She thinks that Two-Bit and Pony are being prejudicial, painting all Socs with the same brush and assuming they have all of the advantages. 

"I'll bet you think the Socs have it made. The rich kids, the West-side Socs. I'll tell you something, Ponyboy, and it may come as a surprise. We have troubles you've never even heard of. You want to know something?" She looked me straight in the eye. "Things are rough all over." (Ch. 2)

After the movies, Cherry asks Pony about Darry.  Pony gets defensive, even insulting Johnny when he gets involved, telling him that he isn't wanted at home.  Pony and Two-Bit discuss how the greasers "have all the rough breaks!"  Pony realizes that he forgot that the Soc girls were there.  They may have problems too, but the greasers and Socs will always be different.