Although the story itself has nothing to do with Russia, the main character and his peers speak a sort of "Russified English" slang, known as Nadsat (which itself comes from the suffix -teen in numbers: тринадцать). For example: malenky means small, and a droog is a friend. A lot of words in the book are of Russian derivation, and the author doesn't provide a key. So, if you don't know any Russian (as I didn't when I read this book), it takes a couple of chapters before you're able to figure out what the hell everyone is talking about.
Although it is very disturbing, it is a very good book.