I'm sure I've posted this story before but it fits:
Back when I was in the Datsun Z club, our president was driving through New Mexico on his way to the national convention in Colorado. As he crested a hill he saw a state trooper writing a ticket. As he passed, the trooper jumped in his car and pulled him over. The trooper said he was going to write him a ticket for 75 in a 65. My buddy, being the friendly guy that he is, mentioned that he saw the trooper standing outside his car and wondered how he could determine his speed without radar. The trooper said when you've been doing this as long as he had, you could determine speed visually. My buddy said OK and took the ticket. After telling the story he told us he couldn't have been doing less than 120 when he crested the hill
And another one:
I was coming up on a known speed trap in Austin doing about 70 in a 30 zone (there were no cross streets, pedestrians, etc.) My view was blocked by an ambulance up ahead and sure enough when the ambulance cleared, there was a motorcycle cop standing there with radar gun in hand. I grabbed all the front brake I could and got it within a reasonable speed quickly. Of course he motioned me over so I pulled right up to him and sat motionless for couple seconds before putting a foot down. We talked for a few minutes then he said he could tell I knew how to ride and admitted I decelerated so fast he couldn't get a radar reading. He wrote me a ticket for 40 in a 30 saying he would have no problem getting that to stick. BTW, the case took 2 years to go to court and was finally thrown out after the prosecutor's bluff that the they were ready didn't faze me