ALICE COOPER has some rock advice for JUSTIN BIEBER:  If you have to puke onstage DON'T turn your back to the crowd.

I just wish he'd kept the adivce to himself because I personally don't want to see Bieber become more rock n roll, I'd rather he fade into oblivion immediately. Ha.

Anyway, Alice is talking about an October concert, where Justin barfed onstage, and later blamed it on wolfing down too much milk and spaghetti bolognese before the show. Hhhmm, yeah I don't buy it.

Alice says, quote, "He came into Phoenix, comes up onstage, turns his back to the audience and throws up.  I [thought], 'Justin, just as a note of professional rock 'n' roll, never turn your back when you throw up. 

"Let the audience see you throw up.  Because that's a moment they're gonna remember.'" 

Now, Alice is NOT a Bieber hater . . . in fact, he thinks he has the talent to make it, but he warns that he's going to have to survive his 20s first.

He says, quote, "If he rides this thing out and still makes records, he's gonna be a seasoned artist in about 10 years, 'cause he makes good records now, but he's got to survive the next 10 years.  The excess is gonna come at him so quick."

Speaking of Alice, he's planning on putting out an album of rock covers . . . but he won't have time to record it until later this year, so it won't be out until 2014.

THE DOORS' song "Break on Through (to the Other Side)" will probably be on it, perhaps alongside "Revolution" by THE BEATLES, "My Generation" by THE WHO, and JIMI HENDRIX'S "Foxy Lady".

Alice says, quote, "We do a thing in our show, which is a tribute to Hollywood Vampires, my drinking club.  And it was Keith Moon, John Lennon, Harry Nilsson, Micky Dolenz . . . a very eclectic bunch of drunks. Half of them are dead, so we do [those] four songs in the show in tribute to them."