Come on, admit it: You spent a bunch of this book periodically scratching your head and wondering why it was named after Shmuel, Bruno's friend who wears the striped pajamas. And then, when you got to the end, you suddenly found yourself with something in your eye as you watched Bruno put them on and sneak under the fence to help his friend find his father.
For much of the story, the striped pajamas are a reminder of the differences between Bruno and Shmuel's lives—differences that can ultimately be traced to Shmuel's Jewish identity and the Nazis' gross injustices against him and his people. His clothes are a visible reminder that he—and everyone around him—is imprisoned, taken from their homes and forced into a terrible situation they have little power to escape. When Bruno asks Shmuel why everyone on his side of the fence wears the pajamas he replies:
"That's what they gave us when we got here […] they took away our other clothes." (14.883)
Clothes are a mode of self-expression, a means of letting the world know who we are. Taking people's clothes and forcing them into tattered uniforms is a way of attacking their individual identities—it literally strips them of the ability to share who they are visually. The Nazis, of course, had other ways of controlling their prisoners, but the striped pajamas are one that Bruno, at the age of nine, recognizes as different. It's a clue to him that something is off on the other side of the fence, even if he can't quite grasp what it is.
The striped pajamas in this book signal more than just the death of self-expression and individual identity—they represent death itself. And friendship. After all, Bruno puts a pair on and sneaks to the other side to help Shmuel look for his dad, an act of true love and support. In doing so, though, he loses his own individual identity, and is seen by the soldiers as one of the imprisoned masses, which is how he finds himself standing in the gas chamber holding hands with his friend.
Yeah, we may never wear striped pajamas again…