If you don’t mind them asking then it’s easier to shrug off the question and smile.
If you are uncomfortable or you are worried about how they might react then I can understand that it may be harder.
Coming out isn’t always easy and dealing with questions from friends can make it even harder.
If you suspect that they already may know then you could ask them “would it matter if I was?” Their response may surprise you.
If you don’t feel like you could do this then you could try telling them that their questions make you feel uncomfortable and that your sexuality is something that you would rather not discuss. If they are sensitive then they will understand, although a mystery can sometimes inspire even greater curiosity.
If you feel that they are asking out of fun or making a joke at your expense then you do not have to dignify their question with a response. Your sexuality has dignity and it’s not a toy for gossipy teenagers to play with. Real friends won’t be in it for the scandal they will be it it for you.
Perhaps next time they ask you, ask them why are they so curious to know? I am guessing that the reason you don’t want to tell them is because you may be worried about how they will react or you do not feel ready to come out yet and that’s okay. You may even feel that you need more time to explore your preference and that’s perfectly okay too. If you ask them why they want to know, you may find that it gives them the chance to open up to you. It is entirely possible that they are cool with it, or already suspect it, and are trying to come up with a way of talking to you about it.
Only you can really know when the time is right for you to come out, but talking about it and asking for advice is a good thing to do and very brave of you. Whatever you decide know that you deserve love and respect and don’t let anybody make you ever feel otherwise.
It gets better.