Seth Rogen
Actor Seth Rogen arrives at the 2014 Vanity Fair Oscars Party in West Hollywood, California in this file photo taken March 2, 2014. As a married former party guy transitioning into suburban parenthood, Rogen wages war with the frat house next door in the raucous new Nicholas Stoller movie, "Neighbors," that screened this weekend as a work in progress at the SXSW Film Festival. REUTERS/Danny Moloshok/Files Reuters

Seth Rogen isn’t a fan of Justin Bieber, and he’s not afraid of the Beliebers lashing out at him. The 31-year-old comedian has some unkind words for his fellow Canadian, saying that the 19-year-old singer is, simply put, “a piece of s***.”

On “Watch What Happens Live” on Wednesday, Rogen didn’t pull back when host Andy Cohen asked him about the controversial tweet he posted in January when Bieber was arrested for DUI.

All jokes aside, Justin Bieber is a piece of shit.

— Seth Rogen (@Sethrogen) January 23, 2014

Rogen wasn’t apologetic, though. And instead of sweetening up his tweet, he added more sharp jibes at the tween heartthrob.

“In my opinion, Justin Bieber is a piece of s***,” the “Pineapple Express” star said.

“He seems like he’s obnoxious and ungrateful and insincere and he puts people’s lives in danger with his horrible, horrible behaviour.”

Rogen wasn’t also shy in naming men that he has “done” it with. Taking a page from Lindsay Lohan’s book, he gave the names of celebrities that he smoked weed with.

“This is really depressing for me to say... I’ve never smoked weed with James Franco because he doesn’t smoke weed. That’s why he’s such a good actor! It’s really sad, actually,” he said of James Franco, whom he has starred with in “Pineapple Express” and “This is the End.”

As for Franco’s younger brother, Rogen said, “I don’t know, honestly. Maybe sometime throughout the years.”

He also hasn’t smoked marijuana with iconic singer Barbra Streisand, but “we talked about it a lot. She smoked weed with Peter Sellers, though. That’s the craziest s*** ever!”

Rogen also named Jonah Hill, Paul Rudd, Sarah Silverman, and Snoop Dogg.