I think that there are many examples of verbal irony throughout the novel.  Part of this is because Bruno sees things in a manner that is fundamentally at odds with how the world of the time sees reality.  From chapter 11, I would spend time examining the irony of Bruno's pronunciation of Hitler's name or title is ironic.  The term "Fuhrer" is morphed through Bruno's language as "the Fury."  This is ironic because it is an apt description of what Hitler was doing to millions of people while others failed to notice it.  At the same time, while Bruno is consistently calling Hitler "fury," it is also reflective of the experience that his own family will undergo at the end of the novel.  The emotional "fury" experienced is being foreshadowed with Bruno's mispronunciation.  It is ironic that while Bruno is saying something that everyone, especially Gretel, deems as wrong, Bruno is actually speaking correctly about what is going to happen.