Eminem Flips Off 49ers Fans During Roller Coaster Day At NFC Championship Game

Eminem had a helluva day in Santa Clara on Sunday cheering on his beloved Lions ... getting into squabbles with 49ers fans -- before sweating out a heartbreaking loss.

The rap legend had suite seats for the NFC Championship Game at Levi's Stadium ... and the day was filled with a roller coaster full of emotions for the Detroit native.

Throughout the afternoon, he was seen chirpin' at San Francisco faithful in his Lions T-shirt -- even flipping off a man who was decked out in a Brock Purdy jersey.

Later in the evening, after Detroit went up on the Niners, 21-7, he was spotted going crazy in his luxury box.

However, when the Lions began to blow their lead, Em could be seen looking super stressed.

Ultimately, Detroit fell, 34-31 ... but Marshall wasn't too sour about it all, he took to X to thank his favorite team for the great year, before promising they'd make a return trip to the NFCCG.