The Boy in The Striped Pajamas is narrated by Bruno, a 9-year old boy from Berlin whose father is one of Hitler's esteemed senior officers. Bruno does not understand all the changes to their lives and is unimpressed by the family's move out of Berlin to a "desolate" place; a home with only three storeys and no banister to slide down.
The sarcasm is present in the double-meaning of certain words, mis-pronounced by Bruno. There has been some criticism leveled at John Boyne, the author as, in German, Bruno's first language, the word "fuhrer" could not be mispronounced as "fury." However, to an English reader, Bruno's insistence on referring to "The Fury" is an understandable mistake for a 9-year old and the reference to the "fury" therefore mocks Hitler and everything he stood for.
Similarly, Auschwitz is pronounced "Out-With" by Bruno. To some this serves as an irritation but to others, it reflects an attempt, not to lessen the significance of Auschwitz (although it has been interpreted this way) but to belittle the Nazis for their attempts to stifle and summarily extinguish everything that is Jewish.