"End of the rope. Then why the hell don't you just let go of it already, huh?" Didn't feel like he was trying to keep a grip on it by much anyway. Sam tried talking to him, he got shot down. They weren't going to get anywhere if they kept doing this to each other. "Save yourself the stress." Of having to worry over his idiot son. The way he acted, the way he talked to him? It all made him feel like John thought he was talking to some twelve year old kid. That twelve year old kid? Sammy? He was grown up now.
There were a lot of things that Sam wanted to say right now. He was angry. The way he was sitting, one hand balled into the side of the seat while the other lingered a few inches away from the handle of the door (it looked like he was about ready to yank it open and jump out - which was actually what he was prepped up for doing when they got to the house), his shoulders squared tightly, mouth set in a thin line. The posture alone said it all. Sam was unhappy. He didn't want to start yelling, but he felt like he was just there. Just at that point where he was about to let everything out. Problem was that Dean wasn't around to keep them from duking it out if he did let go. So he had to keep control for as long as he could.
"Fine. Until you start living your life to the fullest? You don't have any footing to tell me how to live mine. Don't try talking to me again about school or work or whatever the hell it is that I'm doing with Ruby." He cast his eyes out toward the window and glared at the passing scenery. The ride home needed to end as quickly as possible.