The star, clad in a black lacy bra and shorts, welcomed her boyfriend, dressed in a black t-shirt and shorts, to the app with a video of them dancing to the song "Stupid" by Ashnikko. In the perfectly in sync clip, the two mouth the lyrics while shaking their hips to the beat.
On Simpson's newly-created TikTok account, the Australian singer shared a similarly sweet video. Both Cyrus, in a white tank top and jeans, and Simpson, in a black t-shirt and jeans, jump and sway their arms in the air to Shania Twain's "You're Still The One." (The video has since been deleted, but you can check it out here.)