In flannel pajama pants with daring cutouts, Rihanna exposes her butt.

With winter approaching, now is the time to layer up in flannel.

Rihanna, on the other hand, wore flannel pajama pants with a butt cleavage cutout, which is a little more daring than your standard tartan.

Over the weekend, the 33-year-old lingerie magnate displayed her new Savage X Fenty flannel designs on Instagram Stories, first wearing the Tied Up Tartan Sleep Short ($44.95), PJ Raw Hem Sleep Shirt ($64.95), and Bralette ($32.95), before changing into the Tied Up Tartan Open-Back PJ Pant ($49.95).

While the latter looks to be a typical plaid pant from the front, a flip to the side exposes the style's namesake open back and adjustable tie, which is meant to "show off what you want, Savage style," according to the product description.

"Love Rihanna but honestly who is wearing assless flannel pjs," one Twitter user said, while another added, "I suppose I'm officially old since these PJ pants from @rihanna's brand have me shaking my head and thinking, 'Kids these days...'"

Others were more positive about the look, commenting on Twitter, "Rihanna finally produced a sleep set with the booty cut out so we don't have to stroll around in ole'time flannel onesies."

"I gotta say I appreciate the heck out of [Rihanna's] billion-dollar commercial enterprise churning out crap like assless flannel pajama sets," a fourth tweeted of the derrière-baring designs.

It's not the first time the pop diva has added a playful twist to an otherwise mundane wardrobe. Savage X Fenty's Soft Mesh Open-Back Crotchless Leggings ($49.95), which, although seeming like exercise leggings from the front, include a similar unexpected cutaway, split fans in June.

According to Forbes, Savage X Fenty was valued at $1 billion in February, months before Rihanna herself became a billionaire in August.

That's a serious bottom line.