In early 1985, a truck driver in Chicago saw the red flashing lights of a police car in his rearview mirror. He pulled over to the side of the road, in a mild state of panic. He had already collected two moving violations, and knew a third would almost certainly jeopardize his driver's license and, by extension, his job. But he had done nothing wrong, so he jumped out of his vehicle and told the officer just that—then began pleading with the man to cut him a break.

The officer told him to calm down. He wasn’t going to write him a ticket. He pointed to the truck, which had a Canfield’s Diet Chocolate Fudge Soda logo emblazoned on it.

The soda, the cop implored him. I need to get some of that soda.

This is real chocolate. This was not actually in the chocolate soda.peepo/iStock via Getty Images

The 1980s were a period of grand experimentation in the soft drink market. There was Jolt Cola, the hyper-caffeinated concoction that helped power computer programmers and jittery third-shift workers. There was New Coke, the disastrous relaunch of Coca-Cola that threatened to topple the brand’s soda dominance. (They walked it back within months.) And there was a brief flirtation with two tastes that should not have tasted all that great together: chocolate and fizzy seltzer water.

For part of 1985, America was seriously preoccupied with diet chocolate fudge soda.

The cocoa-infused frenzy began after the media picked up a story by Chicago Tribune columnist Bob Greene about Canfield’s Diet Chocolate Fudge Soda, a drink made by the A.J. Canfield Company. Since debuting the drink in 1972, the Chicago-area bottler moved roughly 1.5 million cans annually, primarily in the Midwest, and considered it more or less a regional flavor. (The company’s chemist, Manny Wesber, had formulated it based on a suggestion made by president Alan Canfield in 1971.)

That changed after Greene’s column, in which he claimed the soda had helped him lose weight while on a diet. Dubbing it a “miracle” and that sipping it was like “biting into a hot fudge sundae,” Greene’s enthusiasm was syndicated to more than 200 newspapers nationally. In the first seven months of 1985, Canfield moved 101 million cans in all 50 states, a burst of business Alan Canfield dubbed “fudge fever.”

The surge of interest was due in large part to a perception on the part of consumers that they could indulge in chocolate without having to avoid a scale. (It helped, Greene wrote, to stare at a piece of chocolate cake while sipping it.) Each can of diet fudge soda smelled like chocolate and tasted like chocolate, but it was 100 percent artificial and sweetened with NutraSweet. It contained only two calories. Fans of the drink enjoyed the fact they could get something approximating a dessert without worrying about weight gain. This was, after all, the aerobicized ‘80s, where Jane Fonda workout tapes were stacked on top of VCRs.

Chocolate soda was seen as a no-guilt treat in the 1980s.ayala_studio/iStock via Getty Images

Enthusiastic consumers ran in and out of stores toting cases of the stuff. Canfield received more than 500 calls each day from stores and individuals asking for more of the beverage, so they started running their factories 20 hours a day, seven days a week. Grocers sent empty trucks to Canfield so the distributor could fill them with soda, then rationed supply on shelves—one case per customer—to make sure there was enough for everyone. Fudge fever had commenced.

Other bottlers joined the trend. Royal Crown, Yoo-Hoo, and even Famous Amos all came out with their own versions of a carbonated chocolate soda. (Conventional Yoo-Hoo drinks are, of course, non-carbonated.) One soft drink brand, R.J. Corr Naturals, used real chocolate and charged $2.99 for a six-pack—$1 more than their artificially-flavored competitors.

Canfield grew increasingly annoyed by these many new rivals, and quickly took action. In court, they argued that the word fudge was part of a company trademark and shouldn’t be allowed for rival sodas. In at least one case, a judge sided with Canfield, forcing the Vess beverage company to rename their offering Diet Chocolate Chocolate Soda.

Naturally, not everyone was a fan of the drink, which included more than 40 chemical ingredients. Some taste-testers declared it “horrible.” Undaunted, Canfield released a Diet Cherry Chocolate Fudge version in 1986. But without a national bottling presence, the company was forced to give up some of its chocolate soda marketing share to imitators. In 1995, Canfield was sold to Select Beverages.

The company would ultimately move 200 million cans in 1985, though the fad would be rather short-lived. Today, Canfield’s Diet Chocolate Fudge Soda is difficult to come by, though some still appreciate its distinctive taste. Fudge fever lives.