How we cite our quotes: (Chapter.Paragraph)
Quote #1
Jan had been called up three times but had been rejected on each occasion owing to his poor physical condition, which, given that in those days anyone who could stand even halfway straight got sent to Verdun to assume the eternal horizontal on France's soil, tells you all you need to know about Jan Bronski's constitution (3.16).
It looks like Oskar's uncle Jan was saved from dying in the war (at least for a while) because the dude was too sickly. The army was willing to take just about anybody who could stand on two feet, so the description is supposed to give you an idea of just how weak Jan was.
Quote #2
Oskar couldn't come out from under the grandstand immediately, since SA and SS officers were banging away at planks with their boots for over an hour, snagging tears in brown and black cloth, apparently looking for something within the framework—a Socialist, perhaps, or a team of Communist saboteurs (9.55).
After manipulating the Nazi marching band with his drumming, Oskar knows that he could get into really big trouble. The Nazis don't mess around with people who try to disrupt things for them. And yet Oskar tells us time and again that he doesn't care about politics. He just likes being a trickster.
Quote #3
[M]y uncle, who'd been totally lifeless for some time, shoved his right leg up to the loophole and lifted it in hopes that the scout car might spot it and take a shot at it, or that some stray bullet would take pity on him and graze his calf or heel, providing the wound that lets a soldier retreat with an exaggerated limp (18.43).
Poor Jan has no interest in fighting. He just happens to be in the wrong place at the wrong time when the Germans attack the Polish Post Office. He knows that not being in the army probably makes him look like a wimp, so he hopes to get a superficial battle scar. Jan probably represents most civilians who would rather have no part of this war.