Knicks Star Jalen Brunson Freaks Out After Josh Hart Trade, 'Oh S***!'

Jalen Brunson had the best reaction to his old college teammate, Josh Hart being traded to the Knicks ... 'cause he absolutely freaked out -- yelling, "OH S***!!!"

The Portland Trail Blazers traded the former Villanova guard to the Big Apple on Wednesday ... in exchange for Cam Reddish, Ryan Arcidiacono, Sviatoslav Mykhailiuk, and a 2023 first-round pick.

Brunson was back at Villanova's campus -- where he played from 2015 to 2018 -- to have his #1 jersey retired when the deal went down ... and as soon as someone showed him the news on their phone, he threw up his arms in excitement.

"OH S***!!!," the point guard yelled. "YES!!!"

FYI, Brunson and Hart won the 2016 NCAA championship together ... so it was only fitting Jalen was back in Wildcat territory when he learned about the reunion.

Unclear how Reddish feels about his now-former teammate being this excited ... but Cam barely got any playing time since he joined the Knicks last January, and only started 8 games this season.

Blazers superstar, Damian Lillard had good things to say about his new teammate after the trade, ... saying, "I've always liked Cam Reddish a lot."

"He's one of those guys you just always look like, 'Man, if he gets to the right place, could it just click?' Could you see something come out of it?' I take a lot of pride in pouring into guys [like him], especially in a situation like this."

Hart -- who's shooting 50% from the field -- is nice on defense, plus he's a rebounding machine, averaging 8.2 per game.