She posted a picture after her show in Milwaukee.
Cyrus said she missed her costume change but didn't want to miss the next song- so she just ran out in her undies.
Beyonce, Jennifer Garner, Jane Lynch and a bunch of other celebrities have teamed up for a new campaign to help girls.
It's called "Ban Bossy" and the message is to stop people from using words like "bossy" because it keeps girls from becoming leaders.
The campaign was started by Sheryl Sandberg-- the COO of Facebook.
Justin Bieber recently sat down for a deposition related to a lawsuit filed by a member of the paparazzi.
And it was colorful to say the least.
Justin got particularly heated when lawyers asked him about his ex-girlfriend-- Selena Gomez.
Reporter: "Have you ever talked to and discussed your feelings about paparazzis with her?"
Bieber: "Don't ask me about her again. Don't ask me about her again. Don't ask me about her again. Don't ask me about her again."
Reporter: "Lets take a break."
Bieber: "Don't ask me about her again. Don't ask me about her again."
The photographer who filed the lawsuit claims he was roughed up after Bieber ordered his bodyguard to forcibly take his camera's memory card.
(Martha Shade for CNN's Hollywood Minute)
Copyright 2016 Nexstar Broadcasting, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.