In 1984, MTV gave contest winner Kurt Jefferis a chance to party all weekend with his heroes: the notoriously depraved band Van Halen.

The then-fledgling music-video channel flew Jefferis and a pal from Phoenixville, Pa., to Detroit, where they met up with the band at Cobo Hall. First things first, Jefferis told The Post, “a guy handed me a bottle of Jack Daniels. I took a sip and asked for more.” After being passed a joint, “I took a couple hits and a couple more swigs of Jack Daniels.”

During the show, Jefferis got smashed in the face with cake and showered in champagne by the band members, then he went backstage, where there was a feast of lobster, filet mignon and cocaine.

“I did a couple lines. Then David [Lee Roth, the singer] said, ‘I think Kurt needs Tammy,’ ” Jefferis recalled.

The groupie “took off her clothes and started dancing naked. The two of us wound up together in the shower.”

After that, things got fuzzy. Unbeknownst to MTV, Jefferis had suffered brain trauma a couple of years earlier, as a result of falling 13 feet in a stairwell, and was not equipped to handle Van Halen-level partying.

“I blacked out, and the next thing I remember is waking up in a hotel room bed,” said Jefferis, now 54. Tammy was long gone and “my head was killing me.”

But he still had another day of partying with the band. So Alex Van Halen told him to shotgun a 16-ounce beer. A hung-over Jefferis declined, but the drummer wasn’t taking no for an answer: “Alex said, ‘Kurt, you are not leaving this spot until you drink it.’ ”

By the time Jefferis got home, he was sleep-deprived, in pain and happy to be back at his job as a stock boy at Gimbels.

His wild time is captured in a new documentary short, “Lost Weekend,” premiering Saturday at the Tribeca Film Festival. (The movie “I Want My MTV,” about the channel’s early days, is also part of the fest.) It’s a look at a time you can never imagine happening now, when the break-the-rules channel let viewers in on the fun by gifting them cars, VIP treatment at concerts and even their idols’ homes. The contests sometimes ended in sex, chaos or with winners owing thousands of dollars.

“This was the Wild West of the cable era and [MTV executives] were doing anything they could to connect with viewers,” said “Lost Weekend” co-director Bradford Thomason. “They were flying by the seats of their pants, trying 100 different things to see what stuck.”

There was no shortage of innovative MTV contests in the 1980s: giving away an entire rural Texas town; celebrating the release of Huey Lewis and the News’ “Sports” with a party for 400 in a Michigan teenager’s back yard; sending Prince to a winner’s Wyoming hometown.

There was even a competition where viewers shot homemade videos for Madonna’s “True Blue,” with winners Angel Gracia and Cliff Guest claiming the $25,000 grand prize and a few minutes of “hang” time with the singer.

“That led to Geffen [Records] giving us a deal to shoot videos for their new artists at $10,000 per pop,” said Gracia, who went on to shoot commercials for the likes of Honda.

Other times, things went worse.

When MTV enlisted John Cougar Mellencamp to give away a Bloomington, Ind., house — with the stipulation that the winner had to paint it pink, in honor of the star’s hit “Little Pink Houses” — in 1984, the network should’ve done a little more research.

It turned out “the place we bought was across the street from a toxic waste dump,” remembered former MTV executive John Sykes. “We ended up having to buy another house [for the winner]. That [first] one stayed on our books for five years before we wrote it off.” The second house was indeed painted and the winner reportedly moved in — for two days, before selling it.

In 1989, Judy Frappier snagged a spot in a more desirable neighborhood when she won Jon Bon Jovi’s chldhood home. She, her then-husband and their three children happily moved into the Sayreville, NJ, digs. But it came with drawbacks.

For one thing, they had to deal with fans of the band — “I would be washing dishes in the kitchen and through the window see a camera flash going off,” Frappier, now 56 and retired, told The Post.

But the big downside arrived a year later. Although the prize came with $10,000 (plus a motorcycle and traveling with the band to a week of concerts), it wasn’t enough to cover the taxes on her winnings.

“[The bill] was in the $70,000 range,” recalled Frappier, who now lives in Flower Mound, Texas. “We had to decide what to do quickly in a distressed real estate market.”

They wound up selling the place and ­moving to Houston.

Meanwhile, Patrick McLynn won tax woes and a Batmobile in the summer of 1989.

A prop from the “Batman” movie starring Michael Keaton, the superhero cruiser lacked an engine but was cool nevertheless. So cool that the fabricators who had provided it to MTV angled to get it back.

“I met three guys, who had built the car, in a motel room near the movie theater in Richmond, Va., where [movie co-star] Robert Wuhl was going to present it to me,” said McLynn, now 52, who lives in Richmond and is a technician for movies. “They told me they were willing to get the publicity and then buy the car back. They offered to throw in a Corvette.” He declined, because “it felt like something out of ‘American Hustle.’ ”

Not long after, McLynn wished he had taken the deal. The contest attracted attention via publications, including People magazine, and some reported that the Batmobile was said to be worth around $300,000.

Then the IRS took notice.

“They came after me for tax evasion,” McLynn recalled. With his parents’ help, he wound up paying the government some $70,000. Adding insult to injury, McLynn had signed an agreement that forbade him from displaying the car for money. He ended up storing the immobile vehicle in an industrial park: “My friends and I would go to the Batmobile after work and sit inside, drinking Irish whiskey and smoking joints,” he said. After 13 years, he sold it for a low six figures.

Although McLynn looks back on the experience fondly — “How many people can say they owned a Batmobile?!” — he admitted “it became a burden to me. I offered the Bat­mobile to the IRS but they didn’t want it.”

Sometimes, even the MTV VJs took part in the craziness.

When a viewer snagged a 1983 trip to see prog-rockers Asia play Tokyo, she flew there with MTV talking head Mark Goodman, among others. As Goodman related in the book “I Want My MTV,” the two enjoyed free booze and “felt like we were getting crazy like rock stars. I said, ‘Why don’t you go back in the bathroom and I’ll meet you back there’ … We kept bonking our heads on mirrors and getting leg cramps … The mile-high club is great in theory but not in practice.”

Recounting the incident to The Post, Goodman recalled: “I was married [at the time], so it was f–ked up … But we were out there on the road and having fun.”

And then there was the time MTV treated a lucky winner and friends to a Police concert in Montreal. “It was a complete debacle,” remembered Laura Huntt Foti, author of “The Cusp of Everything,” who tagged along to cover the event for Billboard magazine.

The plan was for Foti and VJ Martha Quinn to take a limo to Philadelphia and fly to the gig with the winners. Adding to the excitement, they were going on the network’s signature airplane. (According to MTV’s Sykes, it was actually a leased Learjet with the network logo taped to its side and removed before take-off for fear “that it would get sucked into the engine.”)

But “the driver got lost and we wound up in Delaware,” said Foti. “Martha and I got to the plane three hours late. The concession stands [at the concert] were closed, and we were starving. The winner quickly shook hands with the Police before we went to our seats — way up in the stadium. The winner was screwed from beginning to end and he started arguing with his wife in front of everyone. She said, ‘Go f–k yourself.’ He said, ‘If I could, I would not have married you.’

“We flew back and a lawyer insisted that MTV live up to its promise of showing ‘National Lampoon’s Vacation’ on the flight,” Foti added. “But the flight was too short to see the entire movie. So we had to circle over Philadelphia until it finished.”

Van Halen winner Jefferis remembers lawyers being less involved with his trip — which now seems like the fever dream of a different era.

“No way could that happen today,” he said. “You’d be signing releases out the wazoo — and that would take all the fun out of it.”