I love that guy who shows up and makes it very clear that he is watching you, usually standing with his arms folded and his feet shoulder width apart, right in the middle of the room, always behind you and to your strong side. He's typically a large man, over six feet tall, and for some reason they tend to have a beard and grey hair. He'll never smile or respond to anyone because this requires total focus. This guy will often position himself so you have to move around him but get within arms length of him to get by.
I call this guy "The Witness." Today, I had one of these guys follow me from the SG counter at Wall Mart, then to the automotive counter where I was getting an oil change, then to Home Depot where I was getting stuff to make a target stand and finally when he followed me over to Petco, I confronted him. I said "If you are not a police officer conducting an investigation, you are stalking me, and if you do not stop I will pursue criminal charges." He said "I'm just a responsible citizen, concerned about people walking around in public with guns." I asked this guy if he planned on following me all day long because, if he was, I could keep him really busy for a long time. He left mumbling something about how he hopes I get shot by the police like that "idiot" at Costco.