It started with Jabrill Peppers not being able to find his blue cleat for his left foot. He had the blue one for the right foot, but he searched his locker and couldn’t find the left one. Then he saw his red cleats and figured a little mix-and-match might be a good idea.

So there was Peppers on the practice field at the Giants training facility in East Rutherford on Monday, looking like Captain America with blue knee-length socks and blue cleats on his right leg and long red socks and red cleats on his left.

“It was a little different look,” mused linebacker Alec Ogletree. “At least he stuck with the team colors.”

To accentuate his appearance, Peppers also wore a long red sleeve and red glove down his left arm, and no sleeve but a blue glove on his right.

“I wanted to have a blue sleeve, too, but I couldn’t find one,” Peppers said.

If his fashion statement wasn’t enough, the Giants safety garnered plenty of attention during practice by inspiring his defense with his play and words of encouragement. Actually, it was trash talk. After a fumble by Saquon Barkley, Peppers barked something about the prized running back being “flustered” and needing to keep his “poise.”

He even had something to say after a returning a punt for what would have been a touchdown had it been a real game.

“I was only running third-quarter speed,” Peppers boasted.

It was all in the name of good competition and preparation for the final preseason game at New England on Thursday.

“We need to pick it up this week,” Peppers said. “Most guys are getting their last chance to show what they can do to try to make the team. We’ve got to get after it while we can.”

This is Peppers’ third NFL season, but it’s a new beginning. Playing for the Giants is a big deal for the native of East Orange, N.J., who was acquired from Cleveland in the trade for Odell Beckham Jr. He is playing not just for a paycheck, but for a purpose. He’s playing for his hometown and his state.

“It’s a Jersey thing,” Peppers said. “It’s everything. That’s who I am. That’s what made me who I am. Now I get to come back, a Jersey product, and little kids can see that it’s doable. You don’t have to fall into [bad] circumstances like everybody else.”

Among his biggest supporters is pro boxer Shakur Stevenson, a Newark native who earned a silver medal in the 2016 Olympics and will fight for the world featherweight title later this year.

“He’s not just a great football player, but he’s a great person,” Stevenson told The Post. “I support him and I appreciate him for all the support he shows me.”

It’s a Jersey thing.

“Everybody in Jersey knows everybody that’s doing their thing on a high level. I’ve been to his last two fights,” Peppers said. “I like his speed, accuracy, head movement and his combination of strength and quickness. No one is staying with him in his weight class.”

Peppers says he used to box when he was kid and still uses some of the training techniques for football.

“I used to do a lot more sparring, but not so much anymore,” Peppers said.

The Giants expect Peppers to land a few hard licks on opposing receivers this year. His leadership and experience is needed in a secondary where rookies Corey Ballentine, DeAndre Baker and Julian Love figure to get plenty of playing time. Peppers remembers the Giants glory years were based on a strong defense and a reliable secondary. He wants to get back to that.

“I was real young when they won those Super Bowls and played in those big games,” he said. “But I know what it did for the whole state. We have a thing called Jersey pride. I want to get back to them days.”

The colors of his team, the heart of his city, Peppers will wear them both with pride.