What do the men do in the trenches, front line, to pass the time, in All Quiet on the Western Front?

In that type of warfare there was not time to pass. You were exposed to the weather, in a trech that would fill with rainwater and sewage and you stood watching for any sign that the enemy was moving. The enemy did the same. If someone on either side raised a head or instrument too high above the grade, the other side would fire on him.

It was constant watching and nerves. Smoking, cards and dice were some entertainments that were common, but any one of them was dereliction. Watching the other side and keeping ready to climb out and overrun the other guy's trench was the job and the life.