'Wicked' Fans React to Movie, Shock and Delight Caught on Faces in Theaters

"Wicked" premiered on Broadway more than 20 years ago ... but, it seems the team behind the film still found a way to shock diehard fans -- 'cause people are posting vids of their friends losing their minds.

The biggest movie of the year opened in wide release in the U.S. Thursday night ... and TikTok is already populating with fan reactions to the movie that's leaving them awestruck.

No spoiler alert here BTW ... 'cause it's unclear exactly which scenes are making people react this way -- though the movie is supposed to be a faithful adaptation of the musical, so if you know the show, you might not be as shocked as these viewers.

Lots of fist-pumping, hands over mouths and shocked laughter ... so clearly, this moment's bringing out visceral reactions in theatergoers.

The new movie is already super "Popular" ... with the flick reportedly raking in $20 million in previews -- with an expected three-day opening between $130 and $150 million.

Of course, even $150 million will be just a drop in the bucket when compared to the budget sunk into making the film and paying for the giant marketing campaign ... though it's a very good start.