Brandi Glanville Dances to 'Last Christmas' in Tiny Bikini Bottoms

Brandi Glanville's shaking it like it's her "Last Christmas" ... dancing to the hit track in just a pair of tiny bikini bottoms with a pal.

The reality television star shared the fun clip to Instagram Saturday ... which begins with her sauntering up in a Santa hat, red sweater and matching thong-style bikini all while Wham!'s hit holiday song plays.

Glanville's friend -- buisnessman James Maas, clad in a red, silk bathrobe -- then pushes her out of the way to grab the spotlight ... sparking a light-hearted tussle between the pair that ends in giggles.

BG captioned the post, "This is what happens when [James] and I try to put up a tree 🎄."

It's a humourous clip from Brandi ... who has more to smile about now then she did around this time last year.

Remember, Brandi first shared a selfie of her drooping face a little more than a year ago ... leading to concern among fans and speculation by pros like Dr. Terry Dubrow about what might have caused the issue.

After a year of searching, Brandi recently revealed she finally has a diagnosis for her condition ... though she's keeping it to herself for now.