Robert De Niro trashes Slack founder Stewart Butterfield: 'I don't give a f--- who you are'

Slack founder and CEO Stewart Butterfield accepted an award at The Wall Street Journal's 2015 Innovator Awards ceremony on Wednesday evening at New York City's Museum of Modern Art. But his speech wasn't well received by at least one of the other stars in the room.

During his speech, Butterfield quipped that he was a long way from San Francisco and that among the stylish crowd of actors and models, he was clearly receiving the "nerd award."

According to Page Six, Butterfield then singled out actor Robert De Niro and said, "I watched 'Godfather II' on the plane ... When you killed Don Fanucci, I liked that."

De Niro, who most recently starred in "The Intern" alongside Anne Hathaway, didn't know who Butterfield was. And apparently didn't think the tech founder was funny.

(Butterfield is the founder of Slack, a work communications platform that has been valued at $2.8 billion by investors.)

"Whoever the last speaker was . . . I thought you were a bit condescending to us actors . . . celebrities," Page Six quotes De Niro. "I'm gonna go on record with you just to say that. And I don't give a f - - k who you are."

Butterfield then tweeted a photo of De Niro and wrote, "I literally got trash-talked by Robert De Niro ... #lifegoals."