I received an sms that if a thief makes you withdraw money at ATM, at gun point. The Pin
No should be typed reversly For e.g.. 1234 shall enter as 4321. If it is done so it will alert the police. How far the message is true. How does it works.

No, it is not true... all that will happen is the ATM will tell you that your pin is wrong. Then the Robber will get mad for you stalling.

Here is the story behind it: snopes.com: Reverse PIN Panic Code

If you ever here about something... check snopes.com - they are the best source for these.