When Seth Rogen called Justin Bieber "obnoxious" and "ungrateful," in addition to many choice words, but the young singer was not going to take it. Bieber took to Twitter to put the funny man on blast.

"Seth Rogan (sic) sorry I didnt bow down when I asked 2 meet u was probably a bit shy and didn't want to be over the top but still. love ur movies."

The "Neighbors" star told Howard Stern the Biebs asked to meet him during a European TV show appearance.

"The kid's a d***," Rogen slammed the pop star.

"He's a good example of someone you meet, who you think you're going to hate him, and then you get to hate him as much as you thought," he added.

The comedic actor did not stop there, and said he had the same impression the second time he met Biebs at an MTV show.

"So I went outside to meet him and he was acting like I asked to meet him! It was very nonchalant, 'Yo man. Sup,' and I'm like, 'What the f***, I don't want to meet you,'" Rogen explained.

"Don't act all nonplussed to meet me. I didn't want to meet you! I was totally cool not meeting you," he said.

"But I was like, fine, I wouldn't have said anything, I was like, 'Aye, he's a bit of a mother*cker. He's young, the kid's a d***.'"

He was also not impressed with the "One Time" singer's outfit choice.

"He literally had a snake wrapped around his f***ing wrist that he was wearing. I was like, what the f***?" said Rogen. "And I talked to him for like five minutes and I just remember thinking, 'F*** this kid.'"

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