There is plenty of irony in this incredible novel. Let us remember that irony reflects a gap between reality and the way that it is presented. There is a sense in which the character of Oskar, the strange and quirky twelve-year-old narrator who tells us his story, and the way that he is presented to us features dramatic irony, as he is unable to recognise how some of his behaviour is so unsuitable in the social situations that he finds himself in. This would be an example of dramatic irony, as we as the readers and the other characters in this novel recognise that what he is saying is unsuitable or doesn't "fit" the social situation whereas Oskar is not able to work this out for himself.
A classic example comes when he meets the first of his list of Blacks, and asks to kiss her:
"Excuse me?" she said, although, on the other hand, she didn't pull her head back. "It's just that I like you, and I think I can tell that you like me."
Oskar is unable to understand why her age of 48 and her married status would make it impossible for them to kiss, and his naivety, or different way of looking at the world is something that the novel explores again and again as we come to realise that Oskar is a child who has an incredibly unique viewpoint.