If there was a festival anthem to this year's Summer Sonic, it was "Girls Just Wanna Have Fun." The overflowing crowd at Cyndi Lauper's Sunday set on the Sonic Stage was mostly made up of women who mouthed every word to her string of hits. And when she finished with her biggest hit, the female members of The Polyphonic Spree and Tilly and The Wall joined her on stage to she-bop ecstatically.