How do Darry and Pony play tug of war with Soda?

Darry and Ponyboy put Soda in the middle of their arguments. He loves both of his brothers, and he cannot stand their arguing.

Soda shrugged. "I don't know. It's just... I can't stand to hear y'all fight Sometimes... I just have to get out or... it's like I'm the middleman in a tug o' war and I'm being split in half. You dig?"