Do you mind...?

I would surely respect his or her feelings. For me the sexuality does not matter in anyway. And if my best friend had not told me about it before I may ask why he/she didn't tell me. I expect the reason can be that somebody can be uncomfortable telling it in the beginning times of a friendship so I would understand that as everybody of us has some reservations about certain things and we would not like to bring up the topic upfront. So okay for me if some one has a genuine reason for not stating something like this at the beginning. But if that is not the case and it was hidden purposefully that I would consider it to be a breach of trust and may rethink my relation with the concerned individual.

there is nothing wrong with it as long as he/she does not invade your privacy as well... If you are not open minded I guess its time to let go of your friendship which can be sad

it wouldn't brother me at all but i'm lesbian lol it wouldn't stop be from being friends with someone. sometimes its really hard to tell people because you don't know how and you don't want to lose them so you keep it from them. maybe give them a way to tell you or bring it up

How would you not know that t? If you are someone's friend you should be able tell, especially if you are their best friend. If not then there is one of two things you need to do. 1: start paying more attention to your friend. or 2: Realize that you might be gay. If you didn't notice your best friend was gay, then maybe you should look at yourself, you're probably gay too. If gay behavior seems normal to you.

I will respect his/her choice. Personally, I don't care about her sexuality as long as it's not me that show in her mind. Beside, being a friend is about accepting who they are and support their choice. You can give advice but it's up to them to listen or not.