The FYF Fest came to a close last night in Los Angeles, with freak-rockers MGMT and My Bloody Valentine bringing the action at the main Carrie Stage to a conclusion. On Thursday night MGMT performed their latest single, “Your Life Is A Lie,” on The Late Show With David Letterman with Andrew Van Wyngarden taking the “more cowbell” creed to the next level by banging on an oversized cowbell throughout the tune. For the band’s FYF Fest performance, Van Wyngarden let actor Henry Winkler, best known as “The Fonz” from Happy Days, bang on the oversized cowbell.

The Fonz had previously teamed up with MGMT for a cameo in the music video for “Your Life Is A Lie.” Watch as Winkler guested with the band last night at the FYF Fest: