Cool as a Cucumber

" 'Gimme five,' he said. 'A real honor.' (pg 226)"

I am mainly citing this quote because I don't understand the motivation behind it. On one hand, the men seem respectful when they approach the dead body of this old Vietnamese man. They shake hands and are careful not to disturb the body to detrimentally. So, they could be just a little bit crazy and really believe that, by treating this man as if he isn't dead, he really isn't. On the other hand, they could be disrespecting him and relishing their victory over him. The entire thing confuses me, but I figure talking to a dead man and giving him his own can of sliced oranges makes them all a little crazy either way. I also find it odd that the men have this reaction. Well, all but O'Brien. He is freaking out, but the rest are cool as cucumbers. A reasonable mind would guess that this is their way of easing their guilt to feel as though they did not actually kill this man, but, in the mind of a soldier, no one can know for sure.