Our visitor from California was trying to open the can of Pepsi he had found in the fridge.  He lifted the ring atop the can … and nothing much happened.

The metallic ring was standing up, but it hadn’t pressed into the top of the can, creating the opening consumers have learned to expect, over the past 40 years.

What he had encountered was a very retro pop top — also known as a pull tab. Practically a museum item for a 20-year-old kid from the U.S. — where pop tops have been illegal for decades.

He thought he had broken the can. When, of course, he was just dealing with an item that could go into a museum, back in the States.

The pop top was seen as a huge breakthrough, when it appeared in the mid-1960s.

Before then, you needed a tool to get into the top of a can. No. Really.

You may have seen one of those tools — about the size of your hand, with a tab at one end for prying off the cap on a bottle, and a semi-sharp triangle at the other end for leveraging into the top of a can.

Seems ridiculous, now, but if you didn’t have access to the tool, you were not going to be able to open your can of soda. Or beer.

Then came the pop top. We were liberated from the tyranny of the can opener.

But there were downsides.

Most had to do with disposing the pop top — or pull tab. It was about an inch long and maybe half-an-inch wide, and it had to go somewhere.

Some people just tossed the pop top on the ground — explaining the Jimmy Buffett line in Margaritaville: “Stepped on a pop top; tore up my flip-flop.”

The pop top was aluminum, and fairly soft, but stepping on it could be a problem, if you were not wearing shoes.

Also, environmentalists were concerned about animals seeing pop tops on the ground and swallowing then, sometimes with fatal results.

Another pop top issue? Many people just dropped the bent pop top back into the can … and sometimes pop tops were swallowed accidentally by people drinking from the can.

So, the pop top was a great advance, but it had problems — and was replaced after about a decade by the handier stay-tab, which is what just about everyone born since 1975 knows. At least in the States.

Turns out, however, that the Pepsi processed in the UAE — and the plant is just a few blocks from where we live — comes with the old-fashioned pop top on it.

What means some of those health and environments risks mentioned above … and profound confusion when someone under the age of 40 confronts it atop their aluminum can.