In my youth while working at gas stations, con artists would try tricks but they didn’t work on me. I would take their bill(s), place it to the side on the cash register till out of their reach and then make change, counting it out on the counter. Too few kids count out money as change now, unfortunately. If the con artist tried anything, like saying they gave me a larger bill(s), I would point to their money still on the side of the till and show them I knew what they were up to. After they retreat, I stick their money in the cash register till. Sometimes I was working graveyard shift all alone, but had a .32 revolver under the counter to keep me company, given me by the boss.
A friend of mine worked at a gas station. After a customer would leave, my friend would drain the gas pump hose into a can. The next customer would unwittingly pay for filling up the pump hose before any gas got into his tank. My friend ended up working for the FBI. LOL
Was it a good ole’ H&R .32? One of the best inexpensive guns ever made.