Foo Fighters hosted their second annual Cal Jam festival in San Bernardino, CA, this weekend, and one of the highlights was a surprise reunion of the surviving members of grunge icons Nirvana—with Dave Grohl on drums and his Foo Fighters bandmate Pat Smear on guitar (Smear was Nirvana’s touring guitarist for a stint), plus bassist Krist Novoselic—which featured both Joan Jett and Deer Tick’s John McCauley taking lead vocals for three songs each, sitting in for the late Kurt Cobain.

Jett handled frontwoman duties on Nirvana’s biggest song, “Smells Like Teen Spirit,” plus “All Apologies” (featuring The Distillers’ Brodie Dalle on bass and Novoselic on accordion) and “Breed,” while McCauley fronted the band for “Serve the Servants,” “Scentless Apprentice” and “In Bloom.”

Jett also joined the Nirvana members at the band’s induction into the Rock and Roll Hall of Fame in 2014, while McCauley fronted the group at an after party following the official ceremony.  Foo Fighters have also welcomed Novoselic on stage during their shows a few times, mostly recently last month in Seattle.

Watch fan-shot video of the Cal Jam Nirvana reunion below, courtesy of YouTube channel Bionic Buzz.