Imagine waking up one morning to realise that one of your songs is featured on a new movie trailer that stars the biggest actor in Hollywood.
Well, that's just a day in the life of JJ and he took to Instagram stories to showcase his stunned reaction.
He wrote: "Hold up...I swear that's my song?"
It seemed like no one on his team managed to inform him of what was going on.
"Lmao no one tells me anything anymore," he added.
Dwayne Johnson posted the trailer on his Instagram and KSI simply commented: "Hold up..."
Some other Sidemen fans in the comments seemed to clock on too.
One user wrote: "KSI's song jump around [shocked face emoji]."
Another user joked: "Yes, Marvel just used your song.
The synopsis for DC's new animation film reads: "The adventures of crime-fighting pets Krypto the Super-Dog, Streaky the Super-Cat and Ace the Bat-Hound."
Johnson is set to play Krypto, the pet and sidekick of Superman.
The star-studded line-up of voice-overs also include - Kevin Hart, Kate McKinnon, John Krasinski, Vanessa Bayer, Natasha Lyonne, Diego Luna, Thomas Middleditch, Ben Schwartz and Keanu Reeves.
Not bad, eh.
Director/screenwriter Jared Stern said: "It was really cool pitching to [DC publisher] Jim Lee.
"I read his X-Men comics growing up and it was just super intimidating, and ended up being the opposite because they were like, 'This is awesome! This is fun!
"We love this as a way into our characters.' They were like, 'Hey, have you thought about this guy being in the movie?' and I was like, 'No, that would be great!' It just kind of expanded from there.
"I think I was just a little bit conservative about how much of it I was using in the pitch. If anything, I was able to let it explode into that world."
The film is set to be released on 20 May 2022 in the US, and 7 October 2022 in the UK.