South by Southwest is just a big party, and King Princess is the girl who brought the good stuff. The 20-year-old played a funny, rocking singalong set Thursday at Stubb’s, clouds of smoke floating through the air like very relaxed ghosts.

Mikaela Straus can be bad sometimes; she can make grown men cry. She also sings with, well, let’s call it an effortless world-weariness. These are songs about desire, and Straus sounds like someone you should listen to about love and lust. A little rasp goes a long way when you’ve got these pipes.

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She’s also your funniest friend.

“We have to get lit for Alicia,” Straus said, exclaiming tickled excitement that singer-pianist Alicia Keys recently name-dropped her. Dedicating Spotify playlist hit “1950” to Keys, she took a puff and tore into the song with all pistons firing.

The venue staff should have passed around red plastic cups at King Princess’ set, because you don’t find relaxed house-party vibes like this everywhere. Things might have gotten a little too lit for Alicia — Straus fumbled the opening to “Talia” a couple times, and when she straddled the stage barricade, she was “really scared of eating s___ in this crevasse.”

Throughout, King Princess kept it gloriously queer: “It seems all the gays came out to play,” Straus said before launching into “P____ Is God,” her ode to the pleasures of the female anatomy.

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It’s always fun to “get” the buzz about an artist when you finally see them live. Straus gives off her own gravitational field. She uses her voice like she’s flexing muscles, and its warmth is narcotic. The only thing I wished for on Thursday was for the backing vocal track to disappear and the band levels to dial down to the ground, just so I could get high on that.