Jaylen Brown and the Boston Celtics are in the midst of a full-fledged victory lap. 

The Celtics hoisted the Larry O'Brien Trophy on Monday night after defeating the Dallas Mavericks in five games. Although Boston dominated in their playoff games leading up to the NBA Finals, the team still faced its fair share of doubters entering the matchup with the Mavs. 

Brown apparently took notice of the lack of support. Shortly after the Celtics won an NBA record 18th championship, he showed off some receipts that he kept handy.

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Jaylen Brown

Jaylen Brown of the Boston Celtics accepts the Larry Bird Trophy after winning Game 4 of the Eastern Conference Finals at Gainbridge Fieldhouse on May 27, 2024, in Indianapolis. (Justin Casterline/Getty Images)

Brown, who was named the NBA Finals MVP, posted a screenshot to his Instagram Stories showing an image of the overwhelming percentage of wagers placed favoring the Mavs over the Celtics in the championship series.

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Just over a decade ago, Brown shared a message on social media about one of his former teachers.

CELTICS STAR JAYSON TATUM TAKES SHOT AT CRITICS AFTER NBA FINALS VICTORY: ‘WHAT THEY GONNA SAY NOW?

"My teacher said she will look me up in the Cobb County jail in 5 years .. Wow," Brown wrote on X, formerly known as Twitter. 

Brown grew up outside of Atlanta and attended Wheeler High School in Marietta, Georgia, which is located in Cobb County. 

Jaylen Brown drives to the basket

Celtics guard Jaylen Brown drives toward the basket during Game 5 of the NBA Finals, June 17, 2024, in Boston. (AP Photo/Charles Krupa)

Less than one month after the post, Brown became a first-round NBA Draft pick.

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Brown's social media post also resurfaced in 2019. At the time, he said the post was intended to serve as a message to young people who experienced an adult shooting down their goals.

"I wasn’t trying to draw any attention to myself. I had no idea this would turn out to be what it was," Brown told Mass Live. 

"It got a lot of attention. If kids look at it the right way in terms of somebody ever said anything that tried to put them down or shoot their dreams down and motivated them to get where they are, I salute that. But I had no intention of it becoming a thing."

Jaylen Brown shoots

Boston Celtics guard Jaylen Brown shoots during Game 3 of the NBA Finals on June 12, 2024, in Dallas. (AP Photo/Tony Gutierrez)

Brown agreed to a five-year, $304 million supermax contract extension in 2023, which represented the richest contract in NBA history. The deal means Brown will earn an estimated average of $60.8 million per year over the life of the contract.

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Brown's teammate, Jayson Tatum, led the Celtics with 31 points in Game 5 as Boston pulled away for a 106-88 victory.

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