Sabrina Carpenter and Kacey Musgraves killed it at the Outside Lands Music Festival in San Francisco, singing one of the most iconic songs ever … and the crowd went nuts!

Sabrina and Kacey sang Nancy Sinatra‘s famous hit, “These Boots Are Made For Walkin'” … and the only thing that was a little disappointing — the 2 singers weren’t wearing boots!

Nevertheless, there was a lot to celebrate … before taking the stage, Sabrina took a sip from an espresso cup to celebrate her hit song, “Espresso,” passing the 1 billion mark in terms of streams on Spotify.

There were a bunch of other stars who performed, including Post Malone, Shaboozey, The Killers, Chappell Roan, Sturgill Simpson and others.

But Grace Jones stole the show. The 76-year-old icon wooed the crowd with amazing costume changes, opening her set 30-feet above the stage. She ended the 1-hour set hula- hooping barefoot wearing a g-string and singing “Slave to the Rhythm.”

Post and Sturgill will perform Sunday night to close out the festival.