The "Party Til You Puke" author had collaborated with Hanson on their annual Fool's Banquet songwriting retreat, and he may have helped give them an edge on those singer-songwriters who score very special One Tree Hill episodes and even more special One Tree Hill commercials. "Go," the first single off Hanson's upcoming album, has the kind of soaring falsetto chorus W.K. would approve. And he might have taught the brothers a few rock-star maneuvers: When insistent feedback derailed the set, middle brother Taylor kicked over the offending speaker, calling the high-pitched whine their "Radiohead moment."

And, when you think about it, maybe Hanson and W.K. aren't such a weird pairing. The brothers are best known for a feel-good hit, while the punk icon entreats fans to start each day by kicking self-doubt in the face. These guys are all about optimism. And though W.K. refrained from fighting personal demons onstage, he did provide a frantic, skittering piano solo during an encore rendition of Cat Stevens's "Peace Train." Go humanity! —Lindsey Thomas