"SHAWTY MANE!! I'M BACK!," Justin Bieber wrote on his Twitter page.

Justin Bieber's MC name is Shawn Mane and he makes an appearance on Chris Brown's mix tape, "Boy In Detention." He dropped a couple of verses in the track "Ladies Love Me," for the singer.

"Baby, I'm your doctor/ I could be your rocker/ Swaggin', I'm not braggin' but I swear that I could rock ya, baby/ I'm not crazy/ I got swag like Patrick Swayze," Bieber raps in a verse.

This may be the first time most hear about Bieber spitting rhymes, but he was a featured rapper in Sean Kingston's track--"Won't Stop" and posted a video on Twitter of himself rapping, last year.

According to MTV news, this is Brown's first-ever rap mix tape release. Not only does it feature Bieber, but also appearances by Swizz Beats, Tyga, Dawn Richards, Wiz Khalifa, and Kevin McCall.

Catch the stars at the MTV Video Music Awards as both have been nominated for awards!

The mix tape was released on Brown's website Friday and was produced by David Banner.