I had cops follow me around all the time a few years back... it got to the point where I pulled over to the side of the road. he pulled over and turned on his lights, came up and had the nerve to ask me what I was doing out at that hour (it was like 1am... on a thursday... and I wasnt swerving/speeding/even coming home from a bar, or in the direction of any that I knew of)
I kindly retorted with a "What is the exact cause and reasoning behind you pulling me over. It's surely not to ask me how my day is going, for if it is, then you're wasting my time and taxpayer dollars"
He promptly found a reason to let me go and left haha.