Los Angeles FC celebrated its MLS Cup championship in grand style Sunday outside its Banc of California home, and the star performance of the afternoon — as in the title game the day before — was John McCarthy, the career backup who killed his hometown Philadelphia Union in the penalty shootout following a staggering 3-3 draw.

McCarthy danced across the stage, showed off his Cup-MVP trophy, led a crowd the club estimated at “more than” 5,000 in chants and cheers, and gave a rousing speech — or, more accurately, rousingly answered questions posed by Max Bretos, LAFC’s play-by-play voice — punctuated with eight delicious F-bombs.

The 30-year goalkeeper is, as he noted after denying Jose Martinez and Kai Wagner at the penalty spot in LAFC’s 3-0 tiebreaker triumph, “a Philly kid through and throughout,” and you could hear it in every declaration.

“If my voice is lost, it’s because I fucking partied so much last night,” he croaked near the end of the nearly two-hour festival on Christmas Tree Lane East, a grassy space immediately north of the Banc in Exposition Park.

Of his reaction when Ilie Sanchez beat Andre Blake to the right post with the decisive finish: “I gotta go in and save another one. I thought the game wasn’t over. I had no clue. Not a clue. I was walking [back to the goal], Ilie jumped on me. I said, ‘What are you doing … holy shit! We fucking won! Fucking we did it!”

The audience, nearly all of it clad in LAFC’s becoming-iconic black-and-gold jersey, roared throughout. If anyone was aggrieved by any perceived affront to decorum, well, that ship sailed when co-president and chief business officer Larry Freedman, addressing those who doubted the club’s resolve and ability to win American soccer’s biggest prizes, offered something of a mission statement for the party while paying tribute to fellow co-president John Thorrington, who, as general manager, brilliantly constructed and rebuilt a roster that claimed two Supporters’ Shields in its first five seasons, something only the original D.C. United, playing in a league with far less competition, had achieved.

“There were so many doubters we encountered along the eight-year journey [from the club’s formation] to this Cup,” Freedman said in the day’s most eloquent remarks. “Those who thought that all we did was focus on our [logo]. Those who thought we would quiver and crumble when we stood next to the giants of MLS. Those who simply thought we were crazy, thinking that anyone would care about a second MLS club in this market. And someone — and you know who you are — kept talking about how John Thorrington had never been an MLS executive before being hired by LAFC.

“Well, after four playoff appearances in five seasons, two [Concacaf] Champions League qualifications, a Champions League final, two Supporters’ Shields, a [Western] Conference championship and an MLS Cup, I’ve got one question for you: How do you fuckin’ like us now?”

Very much, thank you.

Maxime Crepeau, the starter whose red card — on a goal-saving foul outside LAFC’s box five minutes into overtime’s second half — paved the way for McCarthy’s heroics, was the only key figure not on stage, but he was there anyway, FaceTiming on his wife’s phone from his hospital bed in Baldwin Park. The Canadian No. 1, who sacrificed his World Cup to deny Cory Burke a near-certain go-ahead goal, broke his right leg in the challenge and underwent surgery earlier in the day.

“Fucking give it up for Maxi Crepeau one more time,” McCarthy demanded to universal compliance. “The play he made was fucking unbelievable, we will never forget that. He’s a legend for what he did — he saved the game with that play. Don’t ever forget that moment.”

McCarthy then took a step toward the phone, looked Crepeau in the eye and declared” “I fucking love you, Maxi.”

Cristina Dagenais, Crepeau’s wife, led the crowd in a club fight song and spoke after fans serenaded her with a spirited “Maxi Crepeau” chant.

“Max gave his heart and his body yesterday for the club and Los Angeles, and he asked me to say something for you,” she said. “’Guys, we did it. I’m so glad we brought it home. Thank you to my teammates, the staff, the organization and the amazing support since day one as I arrived in the black and gold jersey. This one is for you, Los Angeles. And this is only the beginning. Let’s celebrate tonight.’”

That brought on another round of “Maxi Crepeau! Maxi Crepeau!”