Every group's got one—that snarky, sarcastic wit who can always make a joke no matter how dour the circumstances are. And for the 2nd Company, it's Tjaden.
Whether to keep up morale or just his own sanity, Tjaden can find humor anyplace, anytime, anywhere. When the 2nd Company goes off to string barbed wire across the Front, Tjaden reminds the driver:
TJADEN: And be on time. I don't want to miss my breakfast.
After Paul and Albert trick Tjaden and spend the night with the French women, Tjaden jokingly tells them the next morning,
TJADEN: Mind you, I'm not speaking to you, you traitors.
But Tjaden can't make with the yuks all the time. After a week of constant bombardment and bitter hunger, even Tjaden is ready to snap, cursing the company cook for lacking guts and being "so far behind the lines he can't hear the shooting."
Tjaden isn't just comic relief, though. His comedy has a purpose other than just being funny. His humor follows in the footsteps of a character archetype called the wise fool. This character seems like a dunce, but beneath his badoom-ching wit he's got a handle on the situation that few others can match.
Shakespeare made good use of this character in his plays, so you know it's legit. Feste in Twelfth Night, or What You Will is an example of the Bard using this archetype in a comedy, and the ironically named Fool of King Lear fame shows you the character being put to use in tragedy.
And Tjaden doesn't disappoint his foolish Shakespearean comrades. Here's an example of him acting silly but making a solid point:
TJADEN: Well, how do they start a war?
ALBERT: Well, one country offends another.
TJADEN: How could one country offend another? You mean there's a mountain over in Germany gets mad at a field over in France?
ALBERT: Well, stupid, one people offends another.
TJADEN: Oh, if that's it I shouldn't be here at all. I don't feel offended.
Everyone laughs at Tjaden messing around, but it's clear his engagement with the discussion is on a level above Albert's. His point is that things like "nation" and "nationality" are abstract concepts. A nation is just a plot of land with no personal stake in its own existence.
And it's not like being American, German, or some other nationality is part of one's genetic makeup. Not all people of a nation need to act the same way, or be offended by the same things.
As luck would have it, Tjaden's fate follows a different path from the rest of his 2nd Company comrades. He survives.
Even though we don't see it in All Quiet, Tjaden is the only member of the main cast that survives the war. The character returns in the film's 1937 sequel, The Road Back. That movie tells the tale of four men, Tjaden among them, returning from the war and attempting to reenter society despite their disillusionment.
But that—to quote The Neverending Story—is another story for another time.