Russian slang: "the letter Х"

Question

Someone told me that in Russian slang, people ask each other: Kак дела? (How are you?), to which the obvious answer is Хорошо (Good).
But there's another word that starts with "x" and means the opposite (It may be a slur. I think it means "sh*t," but I can't remember the word), so when when someone asks you "как дела?", you can respond with the slang phrase: Буква Х (Letter X).

These are my questions:

Is this legitimate slang, and if so, is it correct? What's the other word that starts with "x" that means the opposite of "xорошо"?

Thanks!

Answer 1

It's a cliché joke.

— Как дела? — На букву "х", но не "хорошо" // "How are you?" "It's an f-word... and I don't mean 'fine.'"

In Russian, we have the slang swear word хуёво, which means "bad", and which, like хорошо "well", also starts with the letter х.

Answer 2

http://atkritka.com/221817/

Well, the classic (usual) answer is a bit milder.

— Как дела? — Спасибо, на букву "х"(хрено́во).

Answer 3

The former (pre-20th century) name of the letter X was хѣръ. This word currently means penis. Похерить means to break: иди нахер means go to hell. Херово means bad.

The etymology goes as follows: Initially, there was a more obscene, taboo word, хуй, with the same meaning, but later people started using the name of the letter as a euphemism for that word, which, by association, also became obscene.