The birds were flyin’ at Madison Square Garden on Tuesday … all thanks to diehard Knicks fan Tracy Morgan, who couldn’t help but share his frustrations with Sixers star Tyrese Maxey by giving him the finger!!

The hilarious (not so much for New York fans) moment went down in the closing seconds of the Knicks’ Game 5 matchup against Philadelphia … when the former Kentucky Wildcat pulled up from behind the arc to tie things up at 97.

The shot completed the Sixers’ late-game push … coming back from down six in the last 30 seconds to force overtime.

Morgan — who was sitting on Celebrity Row alongside Ben Stiller and Jon Stewart — was clearly upset with his team’s collapse … and after Maxey celebrated the massive three-pointer, he directed his middle finger at the Sixers’ hero of the night.

It didn’t get much better for Morgan — Philly went on to win the game in extra time, securing the 112-106 win to force a Game 6.

Stewart also shared his sadness over the loss … giving Maxey his props while also admitting he’s “getting too old for this s***.”

The Knicks will now travel back to the City of Brotherly Love for Thursday’s contest … and Morgan will certainly be hoping for a different outcome.