It was the last day of 2016 and my friend’s boyfriend was very clear and very upset: The Oreo cookies of his youth were no more, and whatever replaced them tasted like dirt. It was a bold opinion, but he had talking points. Oreos tasted “chalky,” he said, “flavorless,” and “they’re made in Mexico now.” That last point is half-true, but still, America’s favorite cookie switches up its recipe and there isn’t a national outcry? Sounded implausible.

Oddly enough, my roommate texted me, “I didn’t know Oreo cookies go bad, but your Oreo cookies have gone bad,” three weeks later. She went so far as throwing out the cookie after one bite, something she’d “NEVER” done before. We briefly changed the topic before she added, “But for real — it’s not a ploy to take all your cookies for myself. They taste weird AF.” The package she ate from was labeled as “made in Mexico.”

So, was this a thing?

I turned to the internet. Reddit was annoyingly quiet on the topic, but when I typed “Oreo cookies taste” into Google, the first autofill was “different.” The top result of that search is a Facebook comment from July that read, “The Oreos suddenly taste different. Like cheap cookies with that disgusting undertaste.” It was posted on Oreos’ official Facebook page from a woman in Texas — and Oreos replied that they hadn’t made any changes to the recipe.

The post only racked up about a dozen comments, but Facebook users from Indiana, Alabama, Pennsylvania and NYC were as pissed as the commenter, my roommate and my friend’s boyfriend. Oreos suddenly tasted like s–t.

Next I found PissedConsumer.com, a complaints platform where users said the same thing. “Oreos taste soiled,” one complaint from March was titled. “Filling and chocolate cookie doesn’t taste the same!” read another from Feb. 12. One user even posted that he knew 13 seconds was the optimal dunking time for an Oreo but now, “20 seconds and still firm and now gritty.” PissedConsumer has a nifty metrics tool that shows you a timeline of complaints. There’s been a significant increase since November.

Some were angry about the Mexican plant, but others didn’t even mention it, or seem aware of it.

Here’s the quick Mexican Oreos back story: In July 2016, Mondelez International, the company that owns Nabisco, officially shut down the Oreo lines at their Chicago plant. The closing followed nearly a year of rumors about whether it was happening. All of this sparked lawsuits, union-led protests, angry statements from Hillary Clinton and Bernie Sanders and a call for an Oreo boycott from Donald Trump. In the end, Mondelez laid off around 600 workers and cut nine production lines in Chicago to create four new production lines at their plants in Salinas and Monterrey, Mexico. The Chicago plant is still open, and Oreos are still manufactured at plants in Oregon, Virginia and New Jersey (and Canada). But yes, some Oreos are made in Mexico.

It’s easy to chalk up some of these complaints to outrage over outsourcing of American jobs, but I wasn’t convinced that was the case for all of them — and knew it wasn’t the case for my friends.

For the record, I can’t taste a difference, but I love fake cheese and burnt steak and wouldn’t consider my palette a reliable source for anything.

I brought two packages into my office — one from the Mexico plant and one from Nabisco’s factory in Portland, Oregon — to conduct a very unscientific and very unofficial blind taste test with a couple of co-workers who happened to be around. Some didn’t taste a difference, a few thought “maybe” there was something different, and a couple preferred the taste of the Mexican ones.

Food companies do make minor product changes in order to save big bucks; sometimes they talk about it, sometimes they don’t. “Many times companies might change sugar brands etc., in an attempt to reduce the cost of production,” Elizabeth Tomasino, an assistant professor of enology at Oregon State University, said in an email to The Post. She also suggested I’d need at least 200 participants for a blind taste test. I think I asked about 11.

During their third-quarter conference call in October 2015, Mondelez committed to saving $1.5 billion annually by 2018. The closing of the Chicago plant came the following summer. And in November, cookie lovers in the United Kingdom lost their minds when Mondelez increased the gap between the triangular segments on the iconic Toblerone chocolate bar. Ricky Gervais even tweeted BBC’s story about the drama with the comment, “First Brexit and now this.”

Mondelez released a statement saying that yes, they made smaller triangles on just two bars in the UK, and confirmed to MailOnline that it was because the price of cocoa increased. “We had to make a decision between changing the shape of the bar, and raising the price,” Toblerone wrote in a comment on their Facebook page.

After a few weeks of back-and-forth, a representative from Mondelez got back to me about the newest cookie fiasco: “Oreo produced for different markets may have different flavor profiles based on local market tastes.”

Aha!

The email continued: “However, any product that is made for North America consumers has the same recipe and taste profile regardless of what site it is produced at.”

Terrific.

The ingredients on both the Mexican-made and US-made packages are exactly the same, so when Mondelez said they made zero changes to the recipe, I gave them the benefit of the doubt and emailed a bunch of psychologists and physiologists and food science departments to find out if maybe it’s not them, it’s us.

The taste system is inherently complicated. What we like and why is wholly unique to each individual, and shaped by our personal experiences. Our relationships, where we’re from and how we were raised all factor into the foods we crave and the ones we hate. Just like our opinions on music or hairstyles or whether Ross and Rachel were actually on a break, our tastes change and evolve throughout our lives.

Maybe this was like that.

In her initial email, Tomasino wrote that some people have more sweet buds, so they “taste sugar in a different manner.” She added there could be a psychological factor, in the way that drinking wine on a vacation might taste better than drinking the same wine back home. If the taste of Oreos were a memory from your childhood, well, you’re a different person in a different place now.

Or maybe Oreos don’t taste bad, just different from what you expected. Debra Zellner, a psychology professor at Montclair State University, called this a “disconfirmation of your sensory experience.”

For example, Zellner told me, when she was growing up in rural Pennsylvania, there was a local butcher who’d give out garlic-laden ring bologna to the neighborhood kids, who all got so used to his garlic bologna that “anybody else’s ring bologna just didn’t taste good.” Other bolognas weren’t bad, just different, but. This could explain why some of my co-workers preferred the Mexican-made Oreos. This would also mean that, yes, something in the recipe changed.

Production variation is another possible explanation. A former food industry researcher told me how a popular cereal company once moved production from a 100-year-old factory to a new facility in California. They struggled to replicate the taste of the product “no matter how hard they tried,” and chalked it up to the century-old ovens at the previous factory.

Lastly, I spoke with Howard Moskowitz, a psychotherapist credited with reinventing spaghetti sauce in the 1980s. “Mondelez or Nabisco would do everything in its power to maintain the quality of its flagship brand,” he told me. “It’s unlikely that they would ever let the flagship quality falter.”

Great. So why do Mexican Oreos taste like dirt to some people? The answer is (D), All of the above.

Could Mondelez have changed the recipe without telling anyone? Yes. Could they have not changed anything at all? Also yes. Could customers be reacting to the outsourcing of jobs by trashing the taste? For sure. Could newer machines simply bake a different product than 50-year-old machines? Yeah. Does garlic bologna sound, like, weirdly delicious? It does.

Newman-O’s have always been better anyway, in my opinion.