EDIT: Added the cops part of the story

Part 1
<a href="http://video.google.com/googleplayer.swf?docId=-4097602514885833865" target="_blank">http://video.google.com/googleplayer.swf?docId=-4097602514885833865</a>

Part 2
<a href="http://www.youtube.com/v/08fZQWjDVKE&rel=1" target="_blank">http://www.youtube.com/v/08fZQWjDVKE&rel=1</a>

I know Sean advocates being buddies to the police which is all fine and good, but if one tries to question you about something, don't talk to them. This video explains why.

The less your enemies know about you the less ammunition they have against/for you.

100% True.

Recently a friend of mine was at my house ( i was not home ) and there were some kids over who were reported missing. The cops came over, he answered the door, they asked if anyone else was in the house, he said 'i dont think so'.
The cops walked around the house and heard the kids. My friend got charged with obstruction of justice for his ambiguous answer.

Never tell them anything! Some states or laws require you tell your name and address, so do some checking on this.
Also, unless you are in operation of a motor vehicle, you do not have to show your driver's license to the cops.
Local laws may apply differently, and my experience is in the US so... YMMV.