AceShowbiz -

Is Britney Spears gearing up for a "Make Me..." follow-up? According to a source, Britney is shooting a music video for "Slumber Party", fueling speculations that she will release it as the next single off her ninth studio album "Glory".

Britney and her crew reportedly began rehearsing a number for the "Slumber Party" music video last week. A source tells BreatheHeavy that the shoot is currently underway, with anonymous insiders confirming it as well.

"The dancers are going to be wearing lingerie for some scenes and she's designing n creating masks for them," reveals the source. According to insiders, the project is the smallest budget Britney's ever worked with. There is no word about what the concept is or who is directing it yet.

"Slumber Party" is written by Mattias Larsson, Robin Fredriksson, Julia Michaels and Justin Tranter.

Britney recently suffered a wardrobe malfunction during her "Piece of Me" residency at The Axis inside the Planet Hollywood Resort & Casino. While performing a cover of Joan Jett's hit "I Love Rock 'N' Roll" on Saturday, October 23, her halterneck bra top came undone and her left boob nearly popped out.