Very important message for girls in dressing room to do first, before undressing.
Boys please tell to your sister's & lover & your girl friends:
If your fingernail directly touches the image of your nail, then it is a two-way mirror.
2. Two-way mirrors are not hung on walls,they are set into walls or doors.
If there is a wall behind the mirror you can be sure it is an ordinary mirror, because a two-way mirror would be part of the wall.
3. Tap on the mirror,if it is an ordinary mirror it should produce a dull thud.
A Two-way mirror has an open space behind it, so when you tap on a two-way mirror it should produce a much more open and hollow sound.