The band rolled into the grunge classic after performing "By the Way" as the last full song of its set.
Fan-shot footage picks up just as the band winds into the verse. Anthony Kiedis (who does not appear to know the lyrics) mimics the phrasing of Kurt Cobain's original vocals and then guitarist John Frusciante takes over in the chorus.
The band plays through the chorus and cuts off the song before the second verse, with Kiedis announcing the end of RHCP's set and thanking the audience.
Check out the cover via the player above.
The Silverlake Conservatory of Music is a nonprofit founded by Flea and supported by RHCP. The band performs annually at the venue to raise money for the organization, and typically includes some surprises in its show.
Speaking with Guitar World earlier this year, Frusciante named Cobain as one of his favorite guitarists — in the same breath as Eddie Van Halen and Randy Rhoads.
Frusciante complimented Cobain's "visceral" playing style and suggested both he and Van Halen were on his mind as the band wrote and recorded its pair of 2022 LPs, Unlimited Love and Return of the Dream Canteen.