Jon Brion had a weekly residency at the Largo, where he regularly had other musicians come join him on stage. Somewhat spontaneously, Beck was announced as that night's guest. I believe Fiona Apple played with Jon a little prior to Beck's set (I wasn't let in until Beck's set).
I fortunately made it to this show, on a tip. The old Largo venue was extremely tiny, and we jammed in the back. Beck debuted 2 new songs, "The Golden Age" and "Creole Belle," which had never been heard before. Justin and Roger were there to add bass and piano, while Jon moved around a bit--some drums, some extra guitar, etc.
"Rowboat" was played when my brother shouted it out. They threw caution to the wind and tried "Sexx Laws," all raw and acoustic.