Interviews with the cast of This Means War - mostly worth watching because of what happens at around 5.36 and onwards. When he wants to, Tom really does have the best dead-pan face.
Curiously, at the beginning of this interview I was just thinking about how different Tom & Chris seems here: Tom has his legs crossed, wears a necklace etc, while Chris is sitting with his legs VERY wide apart. And then that happened. Ha.