"Lol TBT brb omg OG hb jk LOL (say this 5 times fast #tonguetwatter) #22," she wrote alongside her 'gram of the duo as teenagers. In the pic, Cyrus wears a graphic T-shirt, olive green jacket, dark denim skinnies, and knee-high boots with her long hair styled in waves, while Bieber dons a white jacket, baggy jeans, and electric blue sneakers—talk about nostalgia.
But that wasn't the only thing she 'grammed in honor of his special day. Cyrus also posted a snap of her and Bieber's faces split and put together side by side (likely a nod to the many people who have said they look alike), which she captioned: "Happy Bday J Biebs." Check it out below.