It’s easy to get lost in Venice. The maze of alleyways (calli), passageways (sottoporteghi) and bridges (ponti) can easily disorient even those with the best sense of direction. But if you keep wandering, you’ll eventually encounter a yellow sign pointing toward one of the major landmarks–Ferrovia train station, Rialto Bridge, or San Marco.

Alas, there are no helpful placards for those times when one gets lost in Venetian culture, rather than geography. Our first such moment came less than an hour after we arrived on Saturday–at the local grocery store of all places. You’d think a couple of Americans could figure out a supermarket (after all, we’re the country that invented the damn things) but you’d be wrong.

We had just checked in at our apartment (more about it later), and had to kill some time while the cleaners turned it over from the previous occupants. So we decided to get provisions at the Coop market in nearby Campo San Giacomo Dell’Orio. Everything was going just fine until we got into the checkout line with a basketful of cheese, crackers, wine, cereal-and a couple of apples.

Now, in America, you just throw your produce on the conveyor belt with everything else. The cashier weighs it for you, punches in the magic code, and moves seamlessly on to scanning the yogurt or whatever’s next on the belt. Experienced checkers can ring up almost anything you throw at them without breaking rhythm even a beat.

That’s not how it works in Italy. As we’re now painfully aware.

Forbidden fruit.

I was watching the register and trying to figure out how to ask for a plastic bag, when the apples rolled to the front of the conveyor belt and everything ground to halt. I swear, I even heard the record-scratch noise like in the movies. The cashier stared down his aquiline nose at the two orbs–one Golden Delicious, one Fuji–then oh-so-slowly dragged his disdainful gaze away from the fruit and up to my face. Then he unleashed a stream of utterly incomprehensible (to me, at least) Italian.

I knew we had done something wrong, but I didn’t know what. I vaguely remembered reading something in one of Rick Steves’ guidebooks about not directly handling the produce at a street market, but that didn’t seem to make sense at a supermarket. The best I could manage was a stammering “non parlo Italiano?”

I didn’t think his expression could get more scornful than it already was. But I was wrong. He mumbled something in quasi-English, and I recognized the word “code.” I looked at Maureen, in line behind me and said, “we need the code number for the kind of apple!” Alas, I was only partly right.

Maureen hustled back toward the fruit section, while I just shrugged and smiled like an idiot at the growing line of shoppers waiting behind us. The cashier said something else I couldn’t understand, picked up the apples, and gestured with them toward the back of the store. The woman who was next in line amplified his message with one word–perhaps the only English word she knew: “Go!” So I went, sprinting after Maureen. I thought I heard a groan of frustration behind me, but kept moving.

I had the bright idea (or so I thought) of snapping photos of the chalkboards next to the two kinds of apples we’d bought, and we ran back to the front of the line, which now seemed to snake most of the way down the aisle behind the register–a half-dozen or more Italian women, their eyes shooting flaming arrows of malice in our direction. I showed the cashier the pictures on my phone, and he dropped the apples on the conveyer belt in frustration.

“You need to give weight!” the woman behind us in line said, with the same disgusted tone of voice she might have used to tell her toddler not to pee in the sink.

“Forget the apples,” Maureen said. “We don’t need them.” I nodded at the cashier and made a dismissive wave toward the fruit. He picked them up again, holding them as if they were radioactive, and set them to the side. The bill came to just under 30 Euro, but I handed him two 50 Euro notes. He stared at me like he couldn’t figure out how I had the intelligence to put my pants on before I left the house each morning, then returned one of my bills to me along with a handful of coins. Clearly wanting to put our transaction behind him as quickly as possible, he began scanning the next customer’s items.

Our purchases had piled up at the end of the register, but there was no way I had the nerve to ask for a bag at this point. So Maureen and I silently loaded the items into each other’s arms, and slunk out of the supermarket.

Or we would have, if we’d been able to figure out right away that you have to push a button next to the exit to open the sliding doors. Maureen noticed the button eventually, but not until we’d stood stupidly in front of the door for several seconds, waiting for the non-existent electronic eye to notice our presence, and feeling the very-existent evil eyes of the entire supermarket burning holes in our backs.