My favorite breakfast place in Chicago just opened a new location that’s much closer to my apartment, so I decided to try it out over the weekend. Aside from a few minor hiccups, everything was great. Well, except for one thing: they could only accept Visa and MasterCard, since their Amex account hadn’t been activated yet. And of course, the only thing I had on me was my Amex.

When the cashier learned about the problem, she said I could just come back later that day with cash or another type of credit card. She didn’t request any collateral or demand my contact information. Instead, the cashier just asked for my first name, and then told me her name and shook my hand.

I returned less than an hour later to take care of the bill. But the experience also made me admire the approach that the restaurant had taken. By telling me her name and shaking my hand, the cashier implicitly established a greater level of familiarity and trust. Much like how placing a baby picture in your wallet increases the chance that someone will return the wallet to you, I bet that the name and handshake raise the odds that a customer will make good on the bill.

All else equal, people are more likely to keep promises to people they know. If giving someone your name and shaking their hand builds even a small level of familiarity and trust, then you’ve increased the odds that they’ll come through for you. And since these actions are good for building relationships and loyalty anyway, you really have nothing to lose by helping customers get to know you just a little bit better.