Let's face it, FenrirGreyback was a pedophile. Especially considering that Rowling used lycanthropy as a metaphor for AIDS, which makes him a pedophile looking to spread AIDS to children, not to mention Lupin's worry that he could pass his lycanthropy (as one passes HIV and other STDs) on to his son... and him, having been infected nearly his whole life, he probably did a fair bit of research on his condition that gave him good reason to fear this happening (i.e. he knows of a case where it has actually happened).
For a children's book character, Ron Weasley can be pretty rude. Ron is frequently described as "saying something that made Hermione say Ron!" or making a rude hand gesture.
After the trio is attacked by Death Eaters in the muggle cafe, Hermione mutters that Ron can stick his wand up his arse.