Is it rude to talk about personal fiances.  ?

Just tell him to forget about something that he cannot, at the moment, afford.  That is how most of us were brought up but some youngsters seem to think that, what they want, they should have NOW.  Tell him to start putting some of his money away each pay day to save for things that he wants and, that way, he WILL be able to afford them at some time in the future.  Life is not about having everything we 'want' immediately. We have what we 'need' and save up for the 'wants' in life. 

It can be especially if he's trying to get money from you for something you don't want to be involved in.

If your friend's volunteered his private financial information to ya like that, then you've done nothing rude. Your friend, on the other hand's bloody rude, bombarding you with information what, quite frankly, you probably don't give two bloody flying ***** about! 

Normal people don't discuss those things unless it's relevant to what's being discussed or absolutely necessary. Your friend sounds like a moron. This isn't Ann Landers and has nothing at all to do with books. Put your big boy pants on and say "I don't care about your money situation. It's not my business, and I don't want to hear any more about it." Tell him that you don't care whether he buys 765 lottery tickets per month or invests in a Nigerian prince. And be firm when you tell him not to ask you to get involved with his finances in any way. 

In many countries "one doesn't talk about finances".

Now, I've never understood why that is; actually, it benefits employers much more than employees if the latter don't know what their peers earn. I could imagine that many people would also be less bad in dealing with money if (personal) finances weren't such a taboo.

That said, this doesn't really have much to do with your question (which you've asked in the wrong category).

I don't think at all it's rude of your friend to tell you about his finances. (I would argue that one can talk about pretty much anything with a person one calls a "friend" but that's a different topic altogether.)

It is rude, however, to put you under pressure to cosign a loan. That is very different from merely talking about personal finances.

I don't know you guys's relationship so I guess it might have been fine for him to ask you once, but if you don't want to do that (a smart decision given what you told us about his state of affairs) he should have accepted that.

You already asked this before.  AND put it in the wrong forum just like you are doing here again. 

It's not rude to talk about your own finances. It is very rude to ask someone else about THEIR finances, unless they have indicated that they are willing to talk about them for some reason.

WRONG FORUM. FAIL.

IT'S SPELLED FINANCES, NOT FIANCES. FAIL AGAIN.

You are wise to refuse to co-sign for a loan.  You become liable for the loan if you do.  Don't be a part of his bad financial choices.  I don't consider it rude to talk about personal finances, however, it is certainly audacious to ask you to co-sign or contribute money.

It is not rude to talk about finances but you are fully entitled to say that in your opinion the plans are both unrealistic and irresponsible