These particular characters have deliberately been given stereotypical mannerisms that lead the reader to think that they are the kind of people who would act in such a way. The joke then ends up being on the reader because it turns out that they could not have read these characters and their intentions any more wrong, and illustrates the folly of stereotypes.
If your culture does not have this particular stereotype then I can see how this was lost on you.
Oh ok
Where I live people don’t harass homelesses with spray paint
Cultural differences I suppose
These particular characters have deliberately been given stereotypical mannerisms that lead the reader to think that they are the kind of people who would act in such a way. The joke then ends up being on the reader because it turns out that they could not have read these characters and their intentions any more wrong, and illustrates the folly of stereotypes.
If your culture does not have this particular stereotype then I can see how this was lost on you.
Nothing I’d ever consider doing, either. But there are a lot of cruel people in the world.