As it became clear the song was her massive hit “Party in the USA,” Cyrus continued to have no idea what was going on until the opening guitar chords started playing. With a smile on her face ...

You know what it's like! You're at the club (or, more likely, a CVS), and that coyly optimistic guitar riff—the one you know oh so well—pipes up. Put that toothpaste down: It's a party in the ...