Sokka has that look on his face that says "You took my bride now I take your life" or "You have harmed those that I care about. I suggest you make peace with your God's because I am about to send you to meet them.".
I like the first one better, short and simple. The second sounds a bit out of character for him, and that God doesn't exist in the Avatar world (lol). Imagine if Koh took his bride....oh shit would happen.