Miley Cyrus has revealed that she often warns Justin Bieber not to "become a joke" by getting a bad reputation.

The two singers are friends and the 'We Can't Stop' star told Rolling Stone that she inadvertently has become a mentor figure for the 'Boyfriend' man.

Cyrus added that she doesn't want to see Bieber's true talent being overshadowed by the singer becoming a "joke" figure for "starting s**t" or being topless all the time. When asked if she hangs out with the Canadian, she said:

"A little bit. But not really. I'm not much older than him, so I never want it to feel like I'm mentoring him. But I do mentor him in a way. Because I've been doing this s**t for a long time, and I already transitioned, and I don't think he's quite done it yet."

The 'Wrecking Ball' singer added: "He's trying really hard. People don't take him seriously, but he really can play the drums, he really can play guitar, he really can sing. I just don't want to see him f*ck that up, to where people think he's Vanilla Ice. I tell him that. Like, 'You don't want to become a joke. When you go out, don't start s**t. Don't come in shirtless'. But the thing is, I think boys are, like, seven years behind. So in his head, he's really, like, 12."

Cyrus meanwhile appears on the cover of Rolling Stone magazine as she poses topless in a swimming pool.