Well firstly you're assuming that it IS wrong in the first place, which is another discussion altogether.
If you're a chick and the comment hurts you then it means that deep down you're ashamed of your lifestyle, so taking responsibility and changing would probably be a good step. Alternatively you might be upset because this person is trying to upset you, and people tend to get hurt when people try to purposely upset you.
If it doesn't affect you, then that's cool, you're comfortable with who you are. Great. Haters gonna hate. Just don't cheat on a guy when you're in a relationship, that's never cool.
If you're a chick and the comment hurts you then it means that deep down you're ashamed of your lifestyle, so taking responsibility and changing would probably be a good step. Alternatively you might be upset because this person is trying to upset you, and people tend to get hurt when people try to purposely upset you.
If it doesn't affect you, then that's cool, you're comfortable with who you are. Great. Haters gonna hate. Just don't cheat on a guy when you're in a relationship, that's never cool.