I've always felt a little uncomfortable discussing my income or what I do with my money with friends.
Anyway, the other day, I found myself in a really unusual situation, one I have never ever come across before, so I have probably blown some of the things that have been said/asked since then out of proportion.
Basically, I needed to go to the bank, to change over some cash from scotland. I had a £100 note amongst other notes.
My friend also needed to go to town, and asked if she could have a lift with me, so we went together.
I went to my bank, while she went to hers (a different one).
I had just got to the bank teller, when my friend walked into my bank, obviously she had done what she needed to do at her bank. I expected her to wait within the bank somewhere, or maybe just outside, but she actually walked right up to stand by my side, then proceeded to say loudly 'Wow, a £100 note, where did you get that from?'
I felt really uncomfortable, but didn't want to point out that I thought she was rude to stand right next to me, because she is quite a nice person, and I know she'd be really hurt to know anyone thought she was rude.
The bank teller was asking me a question about my account, a simple question which my friend then answered for me. 
I truly felt like just leaving my friend and the teller to it.
A few days later, same friend was discussing a forthcoming night out, and asked me how I intended on getting to the venue. I said I didn't know yet. I might drive. Friend replies 'You can't drive there, you wont be able to drink'. I said that was a fair point, then I'll probably get a taxi. Friend replies 'You can't afford that, can you? Do you know how much taxi's are. They're not cheap you know, how are you going to afford that, where will you find the money from blah blah blah'
I just find it quite rude when people start asking me direct questions about what I am paid, what I spend my money on etc.
I never know what to say in reply. 
Is it just me? Is it usual to be so open about the finer details of your finances?
Also any suggestions on what to say in response to 'If I was you, I wouldn't do that.' 'You shouldn't buy that, you're wasting your money'
Sorry for the rant. 