To the tune of her legendary 2004 hit Toxic the pair both stood in the shower, before rubbing their mouths along the glass to match the iconic beat.
In Britney's version, the singer wore a beautiful bathrobe and danced on the spot, before opening her mouth in shock and rubbing across the glass.
WATCH: Britney Spears and Sam Asghari make hilarious shower video
She finished her clip by flashing a cute smile at the camera.
Sam added a little bit of a flair to his, as he stood up from the built-in shower seat, did a spin and then rubbed his face across the glass.
The pair share a humongous shower, which has room for three shower seats, as well as an indent in the wall to house some of their hair products.
Paying a heart-warming tribute to her boyfriend, the star said: "Happy birthday to the man that always makes me laugh!!!!!"
The couple have been dating since 2016
She then tagged her boyfriend and posed the question of "Who did it better????" to her fans.
Many of Britney's fans were on her side, with will.i.am saying: "I love this!!! You did it better…!!!!"
"You! You did it better!" posted another fan, alongside an emoji of some hands clapping.
There was a small bit of division, with one fan saying "You both did equally," while another wrote: "This is so great, gave me a chuckle. I think @britneyspears did it better but I'll give it to @samasghari just because it's his birthday."
Another fan called the video "iconic" with someone else calling the cute couple "relationship goals."
"She's a legend," posted one doting fan, while another praised the …Baby One More Time hitmaker as a "quirky queen."
One enthusiastic fan posted: "THIS IS THE BEST VIDEO EVEEEERRRR!"
Fans loved the post from the cute couple
Last month, Sam said he was looking forward to "an amazing future" with the pop singer, following the release of documentary Framing Britney Spears.
Speaking to People, the actor said: "I have always wanted nothing but the best for my better half, and will continue to support her following her dreams and creating the future she wants and deserves.
"I am thankful for all of the love and support she is receiving from her fans all over the world, and I am looking forward to a normal, amazing future together."
His sweet words came as fans continued to discuss the controversial documentary, which was not authorised by the singer.
The documentary explored how Britney had been treated by the media, as well as the conservatorship placed on her following her battles with mental health.
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