Sure! Anything can be a form of self expression - make up, clothes, shoes, accessories, tattoos blue lipstick? Go for it!
For the discussion sake, I'd say that a blue lipstick require the rest of the look to be very creative and unconventional as we can see in the picture in that link. In other words, one must creat a whole image, a costume. It is a fun thing to do, indeed for those who love to come up with different versions /images of themselves. Very brave thing to do, too
But I think most of us just want to find that coveted "me" look, discover who we are. It is hard enough. At least for me
