23. Charli XCX, "Boys"
A daydreaming player's addictive apologia to her girlfriends by the chameleonic British pop heroine. The nursery-rhyme toy-synth melody sinks its hooks in instantly. But the all-star beefcake video doubled its punch, with the singer directing a harem of hotties (including Joe Jonas, Ty Dolla Sign, Jack Antonoff and Mac DeMarco) to show their stuff.