With friends like Miley Cyrus, who needs enemies?As Justin Bieber's single sales continue to disappoint amid his recent bad behavior, his former BFF, Cyrus, has jumped on the anti-Bieber bandwagon with a new Youtube video mocking the former teen idol's Brazilian hookup scandal.

In the clip, filmed during an appearance at London radio station 958 Capital FM, Cyrus inserts herself into a mockup of video of Bieber that was shot by Brazilian glamor model and bodybuilder Tati Neves.

Watch Cyrus' prank vid:

youtube=https://www.youtube.com/watch?v=VwuoSa-OLdE&w=560&h=315

Watch the original:

youtube=https://www.youtube.com/watch?v=36l0tgfFZDg&w=420&h=315

Neves told Brazilian media all about her night with the singer after a friend allegedly leaked the clip, claiming that he was "well-endowed" and "good in bed."

She continued, "A man must know what to do to make me happy. Justin did all that and more."