Rihanna Shows Off Butt in Lingerie While Promoting New Hair Product

Rihanna knows exactly what her audience came for ... 'cause she's promoting Fenty hair products in her most recent post -- but, a whole bunch of people online are going to be captivated by a totally different part of her look.

The singer-songwriter shared a clip to social media which gave fans a look at her brown locks ... turning around to show how her hair looks from the back -- especially when you don't have much on at all.

Check out the clip for yourself ... Rihanna's wearing skimpy thong-style lingerie which covered none of her backside -- so, fans who are interested in a luscious new hair care product got a little strip show to boot.

RiRi's smiling and smoldering at the camera in a different shot ... before leaning over the counter and giving fans quite the view.

Rihanna captioned the photo "keep ya 👀 on the newest member of the @fentyhair fam, The Water Boi Reparative Leave-In Conditioner Spray 💦💦" ... so, she's trying to keep people focused on the hair care, even if everyone else's eyes are traveling further south.

This clip was posted to Rihanna's account early Thursday morning ... not long before she was spotted walking into the courthouse to hear closing arguments in her husband A$AP Rocky's assault case.

Rihanna brought her kids to the trial, which has stretched out several weeks ... and, it's possible a verdict in the case could come down today.