My favourite pet subject is a police officer, stopping you for a spot check or something. They show you their ID, they may wear a uniform, but I know I can fake an ID with some Photoshop (GIMP in my case) work and a laminating machine. Police uniforms are not that hard to acquire too.
Many years ago I worked for Securicor and sometimes did Cash In Transit (you know, those armoured vans full of money).
We had a standard procedure to follow if stopped by a 'Police Officer'. Printed on the back of our receipt books was '
I will follow you to the nearest Police Station'. This was offered up to the armour plated windows of the vehicle by the crew securely locked inside. I've considered having a laminated sign with the same legend written on it to keep in the car, but it's years and years since I was stopped by the fuzz - ever since I sold my red MG, in fact!
TheOddOne