12:55 PM PT -- A source with direct knowledge tells us Taylor Swift did not sneak out of the suite, she walked out with Travis Kelce's family and their entourage.

Taylor Swift fans believe she went to great lengths to sneak out of the private suite where she was watching rumored boyfriend Travis Kelce play football ... Swifties think she left in a popcorn machine.

The fan theory is spreading like wildfire on social media Monday, with Swifties claiming Taylor was inside a large, metallic box that was being wheeled through the Arrowhead Stadium concourse, where tons of folks were waiting to catch a glimpse of TayTay.

Video shows a staffer wheeling the container as one Swiftie claims Taylor's inside the box. It's interesting there's a big bag of popcorn on top of the container instead of inside, plus a law enforcement officer keeping watch.

As you know, Taylor watched Travis' Kansas City Chiefs beat the Chicago Bears, 41-10, Sunday afternoon in KC ... showing up to support him shortly after being romantically linked to the team's star tight end.

Taylor cheered from a suite, where she was hanging out with Travis' mom ... and the two seemed to really get along.

After the game, Taylor and Travis walked out of the locker room area together ... but no one knows how she got from the suite to the stadium bowels without being seen ... hence the popcorn machine disguise theory.

Taylor wasn't too shy once she got near Travis ... they drove off in a convertible and had the top down too.

It's going to be interesting to see where things go for Taylor and Travis ... so get your popcorn ready.

Do you think Taylor Swift and Travis Kelce are the real deal, or just a PR stunt? Vote below.