"I put myself back to together, every night."
Isn't it a sad world when you can relate to that.
I know exactly why he was laughing. Because he just realized, how foolish he was for being afraid of dying during the war and all this time he could have just committed suicide a lot sooner and spared himself from a massive amount of pain and suffering. The entire time, he could have just shot himself in the head but he didn't. The solution was in front of him, the entire time. And then on top of that, he was pretty much already a dead man which makes life for him, just a complete joke. And then the high ranking German officer yelling at him and pointing a handgun at him, made everything even more hilarious. From his point of view, it's like he was being threatened with a water pistol. It's like being in a circus.