Bryce Harper Told Heckler To 'Shut The F**k Up' Before Massive Home Run

Before Bryce Harper sent a baseball to another planet in walk-off fashion Thursday night ... he told a heckler to "shut the f**k up" -- and the scene was hilarious!!!

The Philadelphia Phillies superstar has heard constant chirping from fans this year after signing a 13-year, $330 MILLION contract this offseason ... 'cause he hasn't quite performed up to expectations.

So, after he was 0-for-3 to start the Phillies' game against the Cubs ... a fan let him have it on his way back to the dugout.

"$330 million, 0-for-3," the fan said ...

"Shut the f**k up, stupid!" Harper clapped back.

Of course, there's no doubt the fan did exactly that just an inning later ... 'cause in the bottom of the 9th with the bases loaded -- Harper sent a baseball 413 feet to give the Phils a series sweep over the visiting Cubs!!!

It had to feel good for Harper -- who's now officially busted out of his slump with 7 home runs and 15 RBI in the last two weeks.

Begs the question ... what does Miles Teller know that the rest of the baseball world doesn't?!?!