"Makin up my man into baby billy idol!" Cyrus captioned the post.
The pair also had a message for those who claim that Miley is using Cody to get back at her ex-husband Liam Hemsworth.
Turning their leather jacket-clad backs to the camera, "4 EVER" was embroidered on the back.
They also shared a video of them lip-synching to Billy Idol's hit "White Wedding", a second clip shows Miley and Cody making out and groping one another as Idol's "Eyes Without a Face" plays in the background.
"It’s easy to tease but hard to get release…" Cyrus captioned the second clip, quotes lyrics from the Idol hit.
It's not the first time - and it certainly won't be the last - the pair have packed on the PDA since kickstarting their romance earlier this month, shortly after Miley split from girlfriend Kaitlynn Carter (ex-wife of Brody Jenner), which itself came on the heels of her divorce from Liam Hemsworth.