Travis Barker and Post Malone have some unexpected music sitting in the vault.

While reflecting on the pair’s memorable 2020 Nirvana tribute, the blink-182 drummer revealed that he and Malone also recorded a few hardcore songs together — but fans probably shouldn’t expect to hear them anytime soon.

“We actually recorded a couple of hardcore songs too, which will never see the light of day,” Barker revealed on the Broken Record podcast. “We made crazy songs while we were there too. It was fun.”

Barker also recalled how quickly the Nirvana tribute came together. After initially thinking the idea was a joke, he learned he had just two days to prepare. The drummer admitted he also wasn’t sure how well Malone knew Nirvana’s catalog before they played together — and was blown away by what he heard.

“He killed it. He sounded like Kurt,” Barker recalled. The performance ultimately earned support from Nirvana’s surviving members and raised money for charity.

Listen to the full episode above.