WHO When real-life couple Amy Heidemann and Nick Noonan, both 26, posted a superpoppy cover of Chris Brown's "Look at Me Now" on YouTube last year, it racked up a million views within 24 hours. Says singer-rapper Heidemann, "We eventually got to thank Chris Brown in person for allowing us to destroy his song."
SOUND Karmin calls their style "swag pop" – a glossy mix of enormous Top 40 hooks and rapid-fire rhymes. Says Noonan, "Why can't a white girl from Nebraska rap without swears?"
THE WEDDING SINGER Heidemann played more than 400 weddings before Karmin made it big. "I've got scars on my feet from being stepped on by drunk girls in heels," she says. "I can't wait for the video footage to surface."