Machine Gun Kelly Performs Upside Down Set ... At Packed Lollapalooza

Machine Gun Kelly made a surprise appearance at Lollapalooza Saturday ... mostly upside down.

Fans got an alert on day 3 of the festival ... MGK was there for a special show. Within an hour, he appeared at the Bud Light Seltzer Sessions side stage and performed to ... well, let's just say a more-than-packed audience -- it had 20 times the number of people permitted in the space.

@machinegunkelly this was INSANE #MGK !!!!! pic.twitter.com/7jnFUPt06p

— laura b (@laurabaxter_) August 1, 2021

He performed "Kiss Kiss," more hit songs from "Tickets to My Downfall," and a cover of "Misery Business." But there was more ... "My Ex's Best Friend," "Bloody Valentine" and "Drunk Face."

And then, the stunt ... MGK dangled from the rafters -- upside down no less -- as fans repeatedly screamed, "MGK!!!"

@machinegunkelly x @budlight pic.twitter.com/MIyXNjdywK

— laura b (@laurabaxter_) August 1, 2021

The festival has drawn around 100,000 people, and health officials are super worried it will become a super-spreader event with the surge of the Delta variant.

Fingers crossed.

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