IS SOMEONE WATCHING YOU . . .
THROUGH A TWO-WAY MIRROR?
Actually, you might not be able to tell if someone is on the other side of a two-way mirror and watching you, but you can tell if it's a see-through mirror and be warned.
All you have to do is touch the mirror with the tip of your fingernail, lean in and check for a visual gap between the nail and its reflection. No visual gap __ beware. You've discovered a two-way mirror. My advice is to smile, wave and leave . . . unless you're under arrest at a police station.
Check out the chart below.