Brandon Jennings reacts after being ejected from Game 3. (Jonathan Newton/The Washington Post)

Throughout the Washington Wizards’ playoff run, Brandon Jennings has lamented through late-night phone calls with close friends, telling them he’s not impacting the team enough. Their advice remains the same: Just try to make a difference, Brandon. Be that spark.

On Sunday night, the shorthanded Wizards will look to tie their Eastern Conference second-round series against the Boston Celtics but will do so without reserve forward Kelly Oubre Jr., who has been suspended for Game 4. Someone off the bench will have to be that spark. Jennings must be grinning, ready to play with fire.

In his own way, Jennings made a difference by sending Thursday’s contentious Game 3 into a spiral of bedlam. Jennings returned to his playground days, when he used to talk junk and shame adult men. Early in the fourth quarter of the Wizards’ 116-89 rout, he picked up Celtics guard Terry Rozier, nagging him the length of the court and baiting the second-year player into committing two fouls in one second of game time. Less than a minute later, a cacophony of whistles disrupted the action.

Boston Coach Brad Stevens, usually placid to the brink of apparent boredom, grew enraged. Cameras caught Wizards Coach Scott Brooks snarling and shouting even as his player, Bojan Bogdanovic, was about to attempt a free throw. On ESPN, the broadcast team couldn’t keep up with all the technical fouls.

Chaos had taken over. But, even as he was ushered off the court after being ejected with two technicals, the instigator was smiling.

Jennings had created a spark — and he left behind a game in flames.

Back in Southern California, Jahmond Dantignac watched the unraveling on his 65-inch big screen and shook his head. Turns out, he taught his baby cousin too well.

“Where we grew up, we talked a lot of smack and you didn’t want nobody talking smack to you,” Dantignac said. “So he would do whatever he had to do.”

The Jennings of today — the troll who started a preseason scuffle with Wizards training camp invitee Casper Ware, shoved 7-footer JaVale McGee and pointed a finger gun at Jared Dudley — was burnished on the blacktops of Compton.

“My cousins made me that way,” said Jennings, who is listed as standing 6 feet 1 but that appears to be generous.

“When I was younger, they used to punk me and make me play against older guys. The only way I could play is if I showed toughness and didn’t cry. That’s where it comes from.”

Back then, Dantignac was a standout high school basketball player. Jennings, 14 years younger, was his shadow. Every park and playground that Dantignac visited in search of pickup games, the runt followed.

Jennings was 4 years old — all arms, big head, no body — and yet the kid thought he belonged, too. At first, the cousins shooed him away. But Jennings whined and so they made a deal: Wipe your tears and we’ll let you play.

The cousins were strapping teenagers, and they pushed Jennings around. Hacked the mess out of him. Made him fight and hold his own. This was basketball. Not babysitting.

“Not at all,” said cousin Christopher Phillips, who played high school football and is seven years older than Jennings. “I guess in today’s time it would be considered bullying. But not back then.”

Neither did they spare his feelings. If little Brandon really thought he belonged, then he’d get trash-talked just like everyone else. The big cousins didn’t realize then, but they were creating a monster.

In games played at Laurel Street Elementary in Compton and Rowley Park in Gardena, Calif., Jennings had learned a few AND 1 moves by studying the mix-tape legend known as “Hot Sauce.” And some grown man — the poor guy who had to stick Jennings — unwittingly sprawled into his highlight reel.

“He really made them look silly,” Phillips said. “Then they’d be ready to fight.”

Fight a kid.

Kelly Williams, a renowned coach in Los Angeles youth basketball circles, spotted Jennings at a recreation league game. Williams groans at the memory.

“Just a brash, cocky, arrogant little kid,” Williams recalled. “He was the smallest thing on the court but he had the most swag. Just the most confidence and he just didn’t back from nobody. Just super-ultra-competitive, and that’s what kind of got my attention.

“He was really the best player on the court,” Williams said. “Couldn’t nobody tell him anything different.”

Williams inherited Jennings as an eighth-grade rising star, and later coached him on a loaded AAU team that featured future Cleveland Cavaliers forward Kevin Love and the older brother of Golden State Warriors guard Klay Thompson, Mychel.

Even while playing in big-time tournaments and sharing the court with future NBA stars, Jennings was the box office draw. Williams remembers a very Brandon moment during a championship game in Las Vegas. His Southern California All-Stars met the Chicago Mean Streets; their backcourt comprised of Derrick Rose, the NBA’s most valuable player in 2010-11 and Eric Gordon, who now plays for the Houston Rockets. When Jennings discovered he wasn’t strong enough to keep Rose from driving to the rim, he turned his attention, and his badgering, to Gordon.

“Every time he got rid of his dribble, Brandon was there,” Williams said. “Once he figured Gordon out — ahhh, I mean you’re talking about the clapping in the face, talking to the crowd. It was just on full display.

“With Brandon, he don’t let stuff go,” Williams said. “He’s going to let you know: I’m here.”

Jennings bathes in drama. The subject of his tactics on Thursday against Rozier provoked a devious grin spreading across his face as he said: “It was a mental thing and I got him off his track of what he was supposed to do, which is play basketball. It was on some Dennis Rodman-type mental thing.”

Off the court, friends know a different guy.

When a good friend was having dating problems, Jennings took it upon himself to introduce her to a nice young man. Yes, Khloe Kardashian and Cleveland Cavaliers forward Tristan Thompson are together because Jennings played matchmaker.

A few summers back, when nearly 20 kids were following his every move at an Under Armour tournament, Jennings called for an impromptu shopping spree, telling the excited bunch to grab whatever they liked. He handled the bill. And today Rowley Park now bears his name — with green rubber courts and NBA regulation rims — because Jennings wanted to renovate his old basketball home.

Here in Washington, teammates embrace him.

“He’s not afraid to get under your skin,” Wizards big man Jason Smith said. “I think that’s what he wants to do and that’s a good thing for our team.”

Coaches look past his on-court antics.

“Technicals I can do away with,” Brooks admitted, “but I like guys that compete. I like feisty point guards.”

And in living rooms across Southern California, cousins swell with pride.

Although Dantignac didn’t care so much for the technical fouls in Game 3, believing that Jennings needs to “chill,” he delights in watching the fiery player he once groomed now raise hell in the NBA.

“The one word that comes to mind is just ‘wow,’ ” Dantignac said, then breathed deeply. “I see someone who was determined to do from a young age and didn’t let nothing or nobody deter him from that.”