‘An honest man can sell a fake diamond if he says it is a fake diamond, ain’t it?”

Today’s kingpin CEO of professional wrestling, WWE owner Vince McMahon, would agree with that sentiment. But he didn’t say it. The quote belongs to 1920s wrestling promoter Jack Pfefer. Even around the turn of last century, when legitimate wrestling was vying with boxing as spectator sport, promoters knew the truth: wrestling is boring. Two guys lying on a mat, entangled for minutes at a time. Who’d pay to watch that?

So they faked it. Slaps across the face that missed by inches. Melodramatic headbutts that sent 300-pound bruisers flying onto their backs. Sleeper holds, piledrivers, the suplex body slam that hoisted complicit doomed wrestlers off their feet — and lifted fans out of their chairs in excitement.

In his new book “The Squared Circle: Life, Death and Professional Wrestling,” author David Shoemaker tells the history of the fabulism — but also notes that some of the best stories are the ones that weren’t faked.

The Post asked Shoemaker to pick his favorite true tales from professional wrestling:

1. Doctors use Andre the Giant’s legendary booze intake to determine how much anesthesia to give him

As with everything involving the gargantuan Frenchman, the myth is indistinguishable from the reality, but the legend of Andre the Giant’s drinking almost overshadows his wrestling triumphs.

There are numerous stories of his drinking feats: 119 beers in one sitting, 156 beers in one sitting, a case of wine on a four-hour bus ride, a $40,000 bar tab while filming “The Princess Bride,” an average of 7,000 calories of alcohol intake a day.

When Vince McMahon asked Andre to come back to the WWF as a villain in 1987 to feud with Hulk Hogan and headline WrestleMania III, Andre said that his back was too hurt for him to wrestle. McMahon was determined, though, so he paid for Andre to have surgery and let him rehab at the McMahon family home.

Legend has it that the anesthesiologist responsible for putting Andre under had never before had a giant for a patient and had no idea how much anesthesia to give him. He ended up asking how much booze he normally drank and used that as a guide for his dosage. “It usually takes two liters of vodka just to make me feel warm inside,” Andre quipped.

2. Captain Lou Albano gets run out of Chicago by the mob

Before he became the wacky, rubber-band-wearing manager famous as a part of the WWF’s Rock ’n’ Wrestling Era (and for playing Cyndi Lauper’s dad in her “Girls Just Want to Have Fun” video), Captain Lou was a wrestler in his own right. He paired up with Tony Altomare to form The Sicilians, a tag team presenting itself as Mafia tough guys. While they were wrestling as villains in Chicago, they enraged fans with their tactics — and they also managed to infuriate the real-life Mafia.

In 1961, three members of the Chicago Outfit — supposedly including Tony Accardo — paid The Sicilians a visit and told them to lay off because their antics were giving the mob a bad name. They must have made their point — The Sicilians left town surreptitiously, hightailing it back to the Northeast.

3. Uncle Elmer gets married on WWF television — for real

Usually it’s safe to assume that what happens on wrestling TV shows is fake. But when the October 1985 wedding of Uncle Elmer, a rotund, snaggle-toothed, overalls-clad rube who was the “uncle” of Hillbilly Jim was hyped as a special attraction on Saturday Night’s Main Event, it was even more ridiculous than it sounded on its face — it was a real wedding between Elmer (real name Stan Frazier) and his fiancée, Joyce Stazko.

It’s unclear why Joyce agreed to have her nuptials performed in front of TV cameras — and with her husband-to-be playing the role of a dimwitted hog farmer — but undoubtedly Vince McMahon thought the wedding would make the show a smash hit.

Barnyard animals filled the ring, “Rowdy” Roddy Piper interrupted the proceedings with a string of insults, announcer Jesse “The Body” Ventura heckled the couple over the PA and the whole crowd laughed hysterically through — nonetheless Elmer and Joyce managed to make it through. They walked out of the arena that night as man and wife, and the marriage lasted for six years. Presumably they left the pigs at ringside.

4. Harley Race pulls a gun on Hulk Hogan

In the mid-’80s, McMahon’s WWF went national, threatening the status quo of the wrestling world. Until then, numerous promotions were set up across the country, operating independently under the banner of the NWA.

So, when McMahon started airing national WWF shows and touring his troupe into the cities normally controlled by these territorial groups, the old guard was none too happy. It wasn’t till they toured into the longtime NWA stronghold of Kansas City, though, that the enmity reached a boiling point.

Supposedly, Hulk Hogan was in the dressing room when a local wrestler named Harley Race stormed in. Race walked up to a seated Hogan and punched him, knocking him to the floor. When Hogan sheepishly said that he was surprised Harley wasn’t carrying a gun, Race reached into this jacket and pulled out a .38 Special. Nobody got shot, but Race had made his point. Hogan later claimed that Race actually tried to burn down the WWF ring, though Race denies it. Like most other regional promoters, Race lost a lot of money when the WWF took over, and to make back the money he lost, he ended up going to work for McMahon just a couple of years after the gun incident.

5. Yukon Eric loses an ear to Killer Kowalski

In October 1952, Yukon Eric — a beloved, brawny mountain man, was fighting the nefarious Wladek Kowalski in front of an electric Montreal crowd. The two rivals were deep into their match when Kowalski climbed the ropes to deliver his signature knee drop.

He landed on the side of Eric’s head, accidentally clipped one of Eric’s cauliflowered ears — the grotesquely bloated and hardened ears wrestlers are famous for — and accidentally tore it off the side of his head.

The fans went nuts, and when the papers the next day confirmed the mauling, outrage grew to a fever pitch. The promoter feared for Kowalski’s personal safety, lest some livid fan decide to exact some vigilante justice. So it was suggested to Kowalski that he visit Eric in the hospital to give the appearance of contrition. Kowalski agreed — he and Eric were friends in real life, after all.

There was a reporter from the local paper there covering the plight of Eric, and when Kowalski got into the hospital room, the sight of his “foe” in a ridiculous full-head bandage made him laugh.

“I swear, the first thing I thought of was Humpty Dumpty on the wall,” Kowalski later said. Eric laughed right along, but when the reporter heard the laughter from the hall, he only heard Kowalski’s booming voice, and the headline the next day said that Kowalski showed up only to laugh in Eric’s face.

It only confirmed the fans’ revulsion toward the villain. Suddenly Kowalski had a new nickname — “Killer” — and a new persona as a masochist. Real injures sell tickets, though, and after that, Eric and Kowalski were drawing giant crowds all over the country.

6. Randy Savage kept Miss Elizabeth under lock and key

“Macho Man” Randy Savage was one of the biggest wrestling stars of the 80s and 90s, and his on-screen character was famous for being more than a little nutty, obsessed with treachery and sedition, and overly protective of his ladyfriend, Miss Elizabeth. Any other wrestler who gave her undue attention — from George “The Animal” Steele to Hulk Hogan — was deemed an enemy. In real life, Savage and Liz were married and, as it turns out, the protectiveness was more than just show. Hogan himself has said that Savage would make Elizabeth keep her gaze fixed on the ground backstage so she wouldn’t make eye contact with any of the other guys, and he made sure she had her own locked dressing room to keep her separate from the fray. It’s also frequently reported that as his obsession deepened, he would lock their home — from the outside — when he left, sometimes shutting her inside for days at a time.

7. The Spider Lady (a k a The Fabulous Moolah) steals Wendy Richter’s title — for real

Negotiating a contract could be hell in the WWF.

On Nov. 17, 1985, female superstar Wendy Richter was in the middle of salary talks with the WWF when she was set to defend her WWF women’s title against a masked opponent named The Spider Lady. But when the masked challenger made her way to the ring, Richter — and the fans — could clearly tell it was Richter’s longtime rival, The Fabulous Moolah, under the mask.

While most people probably thought it was just another storyline double-cross, Moolah’s arrival was a legitimate shock to Richter. As The Spider Lady enters the ring, you can see she isn’t acting.

She tries to wrench off Moolah’s mask to expose her, but to no avail — Moolah muscled Richter into submission, and the complicit referee counted a quick three. After the bell, Richter yanked off the mask and exposed Moolah, attacked her, and tried for a pin of her own, but it was too late.

It’s only when the announcer climbed into the ring that Richter realized it was all over. “Ladies and gentlemen,” legendary voice of the WWF Howard Finkel said, “the winner of this bout and new World Wrestling Federation Ladies Champion: The Spider? The Fabulous Moolah?”

Richter was livid, but there was nothing to be done. Moolah had the title back, and Richter would never get her new contract. She was never seen in the WWF again.

8. Bruiser Brody gets killed by a coworker in Puerto Rico

Bruiser Brody was one of the biggest draws before the WWF went national — a 6-foot-plus wild man with a curly, black mane and a penchant for violence. Like many stars of the era — and particularly the monstrous sort of stars — he travelled the world plying his brutal trade.

In 1988, Brody was in Puerto Rico for a big card full of American talent. Before his match, he was called into the locker room shower by Jose Gonzales — a k a Invader No. 1 — a wrestler and close confidant of the promoter (and star) of Puerto Rico, Carlos Colon.

Suddenly, the other wrestlers in the locker room heard Brody moan and looked up to see Gonzales holding a bloody knife.

Brody was a notoriously difficult person to work with, declining to lose any time he didn’t feel like it, but even taken in the extreme, this seemed like a shocking means of working out business affairs.

When paramedics got there, they couldn’t move the enormous Brody, so fellow wrestler Tony Atlas carried him to the ambulance, but it was too late: He died at the hospital.

Gonzalez was charged with murder, but the charges were reduced before trial, and neither Mantel nor Atlas nor any other American wrestler on hand that night was brought back to San Juan to testify. Gonzalez claimed to have been acting in self- defense, and after Colon, a local hero without equal, testified in his defense, Gonzalez was acquitted.

David Shoemaker’s “The Squared Circle: Life, Death, and Professional Wrestling” (Gotham) is out this week.