Nina Dobrev [2] and Julianne Hough [3] took their friendship to a new level on Thursday when they showed their bare butts during a vacation with friends in Idaho. The Dancing with the Stars [4] judge shared the cheeky snap on Instagram, writing, "Full moons! 🌝🌝🌝," as the girls admired the actual full moon in the sky from a distance. The duo has been posting a handful of photos from their vacation, including one bikini-clad shot of the whole group by the pool. While they both showed off their washboard abs [5], Julianne struck an animated pose while Nina rocked her bikini jewelry [6] like a pro. One thing is for sure, they certainly have a fun relationship [7].