In 1987, McDonald’s launched an ingenious sweepstakes based on the game of Monopoly. Customers would purchase sandwiches, fries, drinks, etc., that included peel-off game pieces on the packaging — potentially rewarding them with anything from a Filet-O-Fish to a new car to $1 million. People went wild for it and business spiked by 40 percent for the fast-food giant, which kept it up for years.

But it wasn’t all happy meals.

“It seemed like an opportunity for ordinary people to get ahead, but there were consequences,” said Brian Lazarte, co-director of the HBO docu-series “McMillion$,” premiering Monday, about the contest. In fact, some 50 people would be convicted for cheating.

Blame a man named “Uncle” Jerry Jacobson, who orchestrated a fraud that ran for 12 years and scammed some $24 million from the Monopoly promotion.

Jacobson was an ex-cop-turned-security guard who worked for Los Angeles-based Simon Marketing, which oversaw the contest behind the scenes. Part of his job was to deliver the high-ticket tokens — for cash prizes up to $1 million — to a factory where they were ­affixed to food packaging. One day, in 1989, Jacobson pocketed a prize piece for $25,000 and replaced it with a dud.

But, of course, he wasn’t eligible to cash it in himself. So he gave it to his stepbrother, Marvin Braun, and struck a deal: Braun would turn it in and they would quietly split the money. The scheme worked.

Jacobson was hooked. He started taking every high-denomination game piece he could get his hands on, roping in his friends and family as “winners.” As he grew richer, he joined a classic-car club, took to wearing fancy suits and celebrated at Ruth’s Chris steakhouse.

Braun, however, had a change of heart after the $25K play. While the two men were out at dinner with their wives, Jacobson privately handed a million-dollar token to his stepbrother. “He told me to do something with it,” Braun says in the documentary. “I took it and flushed it down the toilet.”

The stepsiblings stopped talking. But then Jacobson had a chance encounter with a man named Gennaro “Jerry” Colombo, who was ­reportedly related to the Colombo crime family.

She was a single mom who thought this might be her miracle. But she got in deep and could not get out.

According to The Daily Beast, the strangers got to chatting at the Atlanta airport and Colombo mentioned he was on his way to Atlantic City. He unzipped his carry-on to reveal stacks of $100 bills.

Jacobson recognized a potential partner in crime.

“It was a prime situation,” said Lazarte. “Jerry Colombo was larger than life. He could make you laugh or intimidate you into doing what he wanted.”

Colombo would recruit “winners” who paid Jacobson for a game piece — as much as $50,000 for a $1 million prize. But without Jacobson’s participation, Colombo also had these people give him half their prize money.

The scam pretty much ruined the life of Gloria Brown, an acquaintance of Colombo’s wife who got involved in 1997.

“She was a single mom who thought this might be her miracle,” said “McMillion$” co-director James Lee Hernandez. “But she got in so deep and could not get out.”

Brown, a Florida social worker, remortgaged her house to raise a participation payment of $40,000. That upped her monthly bill from around $300 to $1,000 and she was stuck paying taxes on all her prize money even though she’d given half of it to Colombo.

That ended when Colombo died in a car accident in 1998. Jacobson replaced him, but someone called the FBI — which initially ignored the wild story.

Then in 2000, an agent named Doug Mathews spotted the tip on a Post-it note affixed to a co-worker’s computer. Sensing a rise in “my fun meter,” he pushed his skeptical bosses to pursue the case.

Of the 50 or so people who were convicted, most copped pleas and paid restitution. Charged with conspiracy to commit mail fraud, Jacobson got 37 months in prison and was made to pay back

$12.5 million. (He’s now out.)

Taking the stand in a Jacksonville, Fla., courthouse, he admitted: “All I can tell you is I made the biggest mistake of my life.”

How the Big Mac attack went down

Step 1: “Uncle” Jerry Jacobson worked as a security professional for the company that oversaw McDonald’s popular Monopoly game contest.

Step 2: Jacobson would steal winning prize pieces — for as much as $1 million — from his job before they were attached to McDonald’s food packaging.

Step 3: He and pal Jerry Colombo would then enlist “winners” who sometimes paid Jacobson as much as $50,000 to be a part of the scam.

Step 4: The “winners” would then cash in their pieces and give Colombo a cut.