Phillies Celebrate NL East Title With Shirtless Dance Party

The Philadelphia Phillies clinched their first NL East title in over a decade on Monday night ... and they celebrated in epic fashion -- by stripping off their tops and dancing the night away!!!

It all happened following the Phils' 6-2 win over the Cubs  ... when the team hit the locker room to bask in the glow of their big accomplishment.

Owner John Middleton got everything started when he told the team he wanted his "f***ing trophy back" -- which sent the players into a frenzy.

Check out clips from the ensuing party ... the guys -- including Bryce Harper -- ditched their shirts and then doused each other with a ton of beer and champagne.

Kyle Schwarber, Alec Bohm and the rest of the guys clearly had fun too ... belting out their de facto playoff anthem -- "Dancing On My Own."

While it's unclear how long the team celebrated the moment ... they undoubtedly didn't go all night -- as the team has to play another against the Cubs on Tuesday evening.