Jaylen Brown Hit With $25K Fine For Throat-Slash Gesture

Jaylen Brown is paying the price for how he celebrated his insane dunk over Detroit Pistons forward Isaiah Stewart ... with the league hitting him with a hefty fine over it all.

The play in question went down with 12 seconds to go during the Celtics' win over Motor City on Wednesday night, with Brown hitting a nasty poster on Stewart to get the TD Garden going crazy.

In the moment, the 28-year-old emphasized the highlight by making a throat-slashing gesture toward Stewart -- and it turns out the NBA wasn't a fan of the move ... 'cause the league announced he will need to fork over $25K for "making an inappropriate gesture on the playing court."

The fine probably didn't surprise Brown ... 'cause postgame, he told reporters he expected to hear from the Association over the viral play.

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While $25K may seem like an eye-popping number to a fair amount of people ... Brown won't really feel its effects -- as he signed a five-year, $304 million deal with the Cs back in July 2023.

Brown would go on and help lead Boston to a 130-120 victory over Cade Cunningham and the Pistons ... leading the way with 28 points, nine assists and six rebounds on the night.