With the Mets down two games to none in the 1986 World Series against the Red Sox, a crucial Game 3 was about to start in Boston. Cocky Mets leadoff hitter Lenny Dykstra stood in the on-deck circle taking practice swings, while star Bosox pitcher Dennis “Oil Can” Boyd tossed warm-up pitches from the mound. In his new book, “108 Stitches: Loose Threads, Ripping Yarns, and the Darndest Characters from My Time in the Game” (St. Martin’s Press), out Tuesday, Mets pitching great Ron Darling reveals how his teammate unleashed the most vile, racist vitriol he’d ever heard against Boyd — a subplot of that historic series that was never made public. Darling believes the verbal assault changed the momentum of the series . . . and left him with lasting regret.

I only played a few hot minutes with Dennis “Oil Can” Boyd, the momentarily great Red Sox pitcher who featured significantly in the team’s turnaround in the late 1980s. We were teammates on the Montreal Expos for a couple weeks in 1991 — but we had a history before that, of course.

Dennis was one of the workhorse stars of the Red Sox 1986 pitching staff. He’d won 16 games that year for Boston and was slated to start Game 7 of the World Series against yours truly, before a rainout pushed the game back another day and left-hander Bruce Hurst, on closer-to-full-rest, was tabbed instead — here again, against yours truly.

In Game 3 of the 1986 World Series, though, Oil Can was on the receiving end of the ugliest piece of vitriol I’ve ever heard — in a bar, on a baseball diamond … anywhere. It was right up there with one of the worst, most shameful moments I ever experienced in the game, and one of the great shames of the exchange was that I sat there with my teammates and didn’t do a damn thing about it. In fact, it resulted in a momentum shift that probably turned the Series around for us, and like most of the other guys on the bench, I stood and cheered at the positive outcome.

Recall, the Mets had dropped the first two games at home in that Series — a nail-biter and a laugher. Going into Game 3 at Fenway Park, on the heels of that lopsided loss at Shea, we were feeling the pressure. I was tempted to write that we were really feeling the pressure, but this team wasn’t like that. This team was arrogant, always believed it would win it all, never mind what it said on the scoreboard or in the box score. Still and all, it was a must-win for the good guys, only we didn’t exactly come across as good guys on this.

The hero of Game 3 for us was also the a–hole of the game — Lenny Dykstra, one of baseball’s all-time thugs. You know how there always seems to be a guy in every organization, in every walk of life, who gets away with murder — murder being a figurative term in this case? That was Lenny. He was a criminal in every sense, although during his playing days his crimes were mostly of an interpersonal nature. He treated people like s–t, walked around like his s–t didn’t stink and was generally a s—-y human being — and, just maybe, the most confident, cocky player I would ever encounter. It was after he left the game, though, that his behavior took a truly criminal turn; he ended up being sentenced to house arrest on a bankruptcy fraud indictment, and he was also up on drug-possession and grand-theft-auto charges, for which he received a three-year prison sentence.

Not exactly the poster boy for America’s game, huh?

Lenny was leading off for us that night, as he did most nights when he was in the lineup, and as Oil Can was taking his final warmups on the mound, Lenny was in the on-deck circle shouting every imaginable and unimaginable insult and expletive in his direction — foul, racist, hateful, hurtful stuff. I don’t want to be too specific here, because I don’t want to commemorate this dark, low moment in Mets history in that way, but I will say that it was the worst collection of taunts and insults I’d ever heard — worse, I’m betting, than anything Jackie Robinson might have heard, his first couple times around the league. Way worse than the Hollywood version of opposing players’ mistreatment of Jackie that was on display in “The Jackie Robinson Story.” Way worse than whatever Kevin Garnett had famously said to get under Carmelo Anthony’s skin the night Melo went looking for K.G. in the locker room after a Celtics-Knicks game in 2013.

And yet whatever Lenny shouted at Oil Can out there on the mound that night might have had the desired effect, because Dennis looked rattled. It’s amazing to me, looking back, that there’s no footage from the game revealing Lenny’s treachery. He was out there shouting this stream-of-unconscionable s–t in plain sight, in earshot of anyone in one of the front rows and certainly in range of the cameras and microphones that had been set up to record the game, but I guess the attention was elsewhere.

To be clear, bench-jockeying has a long and fine tradition in the game, and there’s a fine art to it, but there are lines that are not meant to be crossed. Wives and girlfriends are usually off-limits, except if a taunt is offered in a benign, nonspecific way — as in, “Tell your wife to stop calling my room!” (In popular usage, offered by a beer-soaked fan taunting you from the stands.) Racial or religious or sexual slurs are typically out-of-bounds as well. For the most part, the razzing is limited to the target’s physical appearance or his skills as a ballplayer — as in, “You can’t even run to first without getting gassed.” Or, on an attempted bunt: “Who’s gonna run for you.” Or, apropos of pretty much anything: “You ain’t got s–t today.”

But this stuff coming out of Lenny’s mouth was beyond the pale.

Unprintable, unmentionable, unforgettable. And, like I said, he was landing his punches: First at-bat of the game, Lenny smoked a 1–1 pitch deep down the right-field line for a home run, igniting a four-run rally and setting us up to take back some of the momentum we’d lost in the opening games at Shea.

Lenny came back to the dugout and collected the high-fives and huzzahs that came his way, and for all I know, I was right there with my teammates, thrilled to be back in this thing.

It’s only in retrospect that I started to feel somewhat complicit and that by accepting the gifts that fell Lenny’s way as a result of his ugly treatment of the opposing pitcher, I was an accomplice of a kind.

From “108 Stitches” by Ron Darling with Daniel Paisner. Copyright (c) 2019 by the authors and reprinted by permission of St. Martin’s Press.