Several decades ago, when I was a teenager, I was shopping in a department store. IIRC, I was looking at 8-track tapes. (OK, many decades ago...
). I noticed a guy hanging around watching me, and following me around the store, and I guessed that he was a loss prevention guy. Back then, I wore cowboy boots and a cowboy hat. Being a teenager, with more ideas than smarts, I walked into another aisle and slipped my wallet down into one boot and put my car keys under my hat. The guy thinks I've tried to conceal a tape or something, and comes up to me and wants to know what I have hidden. I was still in the store - hadn't yet walked past the register or out the door. I suspect today they would at least wait until the suspected shoplifter was outside.
Anyway, when I showed him my wallet and keys, he got pretty irate, and told me he'd be watching me every time I came in after that.
I thought it was kind of funny at the time, I guess. Chalk it up to being a teenager.
But like this present day loss prevention dude, he wasn't very good at his job, if I noticed him so easily. I never even thought about shoplifting anything so I wasn't looking out for anyone, and yet I realized what he was doing.