A childhood belief about ghosts

I found out about The Bloody Mary horror legend a few years ago. I heard that when you chanted her name three times she would come out of a mirror and kill you or scratch you. Well I got it into my head that if you think about her, and chant her name in your head she will also come for you. Then I thought, If she can come out of a mirror, She would also be able to come out of every refelctive surface. I have to cover my eyes away from my TV screen and my Computer screen at night now.