Dean had never seen Castiel laugh before. He had seen him smile softly when Sammy or Dean had made a joke but he had never seen him laugh.
And by the God Dean was still unsure existed could he laugh. When his angel laughed he really laughed. He threw his head back, opened his mouth wide, and let out a roar of laughter that was (somehow) gentle. His eyes sparkled with happiness and amusement, and his shoulders shook in a way he had once mocked Sammy for.
Dean loved the way Castiel's laugh just as much as he did him. He just couldn't beleive that the first tie he had laughed was at a show named "Glee".