From PEOPLE Magazine Click to enlarge
Miley was psyched to go to The Factory in Franklin, Tenn., last Nov. 21, but for all the wrong reasons. "I thought I was going to a concert," she recalls. "My sister Brandi was like, 'We have backstage passes to see Paramore so come around back,' and my mom was like, 'I'll walk you in because I don't want you to get mobbed.' " Instead, Miley ended up shocked when 250 partygoers yelled "Surprise!" as the singer made her way into the '80s-themed birthday bash painstakingly planned by her mom, Tish. "I had no idea," says Miley, who celebrated her real 15th birthday two days later with a Nashville concert.

After changing into an early-Madonna-era outfit that Tish had flown in from L.A., Miley greeted guests, including former classmates and famous friends like Taylor Swift. Then, after downing some pizza and cutting into her marble cake, it was time for the birthday girl to hit the dance floor. "Miley cut loose," says party planner Ellen Appleton. And she wasn't alone. "The dancers from Miley's tour taught me the Pop, Lock & Drop It," says Tish. "That was really fun!"

THROW A PARTY LIKE Miley's!
The woman who helped plan Miley's party shares her secrets on how to pull off a retro extravaganza

BEANBAG CHAIR
Partygoers plopped down on these. $80.99; thebeanbagchairoutlet.com

SLINKY
"There were Slinkys on each table," says planner Ellen Appleton. 98 cents; centurynovelty.com

MINI LAVA LAMP
"These ended up being favors for the kids!" says Appleton. $11.69; coolstuffcheap.com

PILLOWS
Appleton used these to jazz up the couches. $22; wakeupfrankie.com