A couple of days back a sweet visitor was tapping one of the windows of my office. It kept tapping for a few minutes and got us curious to what was happening.
It turns out that our windows are tinted and that from outside it was acting like a perfect mirror. The bird saw another bird and was for some reason trying to get its attention(looked like it was trying to attack it :P ) The curious display happened for over 15 min.
One of my colleagues suggested at this juncture that we open the window and see if it would come in. I was too busy taking photos to stop him from opening the window and the sound scared the bird away :(