Miley Cyrus has mocked Justin Bieber's naked photo.

Miley Cyrus' edit of Justin Bieber

Miley Cyrus' edit of Justin Bieber

The 'Boyfriend' hitmaker shared a nude snap on Instagram showing him exposing his bare backside yesterday (06.07.15) as he looked out to sea and now his pal Miley has edited the image to enlarge his pale derriere.

Posting the picture online, the 21-year-old star wrote, "Look", with the 'Wrecking Ball' singer changing the image and reposting it on her own account, writing, "Bieber got back!"

Although the jokey picture made a mockery of Justin's skinny figure by giving him a Kim Kardashian West-sized butt, fans of the pair clearly found the prank hilarious as they showed their approval in the comments.

One Instagram user wrote: "Haahahhahahah this is so funny! Love you Miley (sic)."

Another user added: "omg. You are too funny. Love u girl. @mileycyrus (sic)."

Earlier, Miley shared a photo of Rihanna's rear-end shortly followed by a close-up of Justin's photo, writing: "Bieber VS Rihanna (sic)."

The 'Where R U Now?' singer - who is currently holidaying with his pal Joe Termini - has not responded to Miley, although it's not the first time she has mocked her fellow pop star.

Back in April Justin posted an image online of him with his hands clasped together and his hair in a tight ponytail, which the pesky musician imitated on her own account.

And in an interview, she joked Justin Bieber was trying to impersonate her when he bleached his hair blonde earlier this year.

She quipped: "I did see Justin the other day and I thought I was looking at a mirror and then I realized that it was Justin Bieber!

"My double life, I never was ever Hannah [Montana], I was always just Justin Bieber and that was my decoy to avoid the fact that I'm actually Justin Bieber."