Zach punches Seth and it was fucking awesome. I think the title is really clever.
Episode description from TV Guide:
"Ryan's chemistry with a classmate opens Marissa's eyes, while Seth's experiment with being Summer's “friend” succeeds only in getting him a job. On the grown-up front, Caleb's arrest leads to a shakeup at the Newport Group that could leave Kirsten at Julie's mercy. The Walkmen perform."