A couple of friends and colleagues, who have the habit to ask me this question, without providing any context of why they ask. If it was the case of "Where are you? We are going to X and we can pick you up", I'll gladly respond if I'm available, but a simple question just for curiosity is uncomfortable to me to respond.
How can be possible to respond to the plain question politely, in order that the other person doesn't feel bad for asking me or feels that I'm being rude with him/her?