Steve-O Calls Out Demi Lovato and MGK to Do 8 X 10 Challenge (Exclusive)

Demi Lovato and Machine Gun Kelly: consider the gauntlet thrown.

Steve-O has called out both singers by name to take up his 8 X 10 challenge.

The Jackass legend began raising impressive sums last year by selling signed 8 X 10 prints of himself pulling some trademark wacky stunts, such as backflipping off a three-story building and duct-taping himself to a freeway billboard.

But it wasn't until he incorporated a celeb pal did he see the numbers really take off: a double-autographed photo of both him and Tony Hawk pulling a simultaneous wall ride raised a whopping $480,516.29 for Hawk's Skatepark Project... and now he's daring more to get involved.

"I'm going with... Machine Gun Kelly," he challenged while out in LA last week. "Yeah, I think he could sell a lot."

"Machine Gun Kelly is such a stunt-y guy; he's climbing up billboards, he's climbing all over everything during his concerts — I think he could do a really epic photo."

Talk of "The Dirt" star clearly reminded the stunt supremo of another crazy anecdote from his early days, which led to another idea for a celeb charity photo: He recalled how as a 13-year-old huge Motley Crue fan, he learned they were playing in his city and spent hours on the phone, calling every hotel and asking for a room booked under their manager's name.

"And it worked," he grinned. "The manager was so impressed that he gave me backstage passes. So I have a picture of me and Tommy Lee from 1987, and I'm this little kid — we're both little kids!"

"If we printed those pictures, and both Tommy Lee and I signed them, that would be a big one."

But the celeb he thinks would make the most money in the 8 x 10 Challenge?

"Oh my God — Demi Lovato would be a big one. I'm calling out Demi Lovato."

Steve-O also explained a little bit about why he is issuing the challenges, and why now.

"With this pandemic, how many people lost their livelihoods? How many people can't eat? It's heartbreaking," he said.

"And anybody who is in a position to help with a huge following, it's such an easy thing to do, it's such a fun thing to do. You print a cool photo, you sign it, you sell it for charity, you give 100% of the proceeds to a charity of your choice."

The money he's managed to raise so far, he insists, is just a fraction of the good that can be achieved.

"I came up with over $600,000 for charity last year — and that's me, I'm not a big deal," he said. "Let's get everybody."