Robert DeNiro was fuming in an argument with Jay-Z at Leonardo DiCaprio’s birthday party in New York.
The legendary actor allegedly scolded the rapper for failing to return not just one, but SIX of his phone calls.
De Niro called Jay on several occasions to plan the project, but his calls were never so much as returned.
The insider said: ‘Bob wasn’t in any mood to make polite conversation.
‘He told Jay that if somebody calls you six times, you call them back.
‘It doesn’t matter who you are, that is just rude.’
De Niro humiliated Jay in front of the likes of Martin Scorsese, Jamie Foxx and Cameron Diaz.
Even Beyonce couldn’t get him off his high horse.
The source said: ‘De Niro kept telling him that he thinks he’s the man, but that he was disrespectful.
‘Beyoncé came over, but that didn’t calm Bob down.
‘It was the talk of the party. Everyone was saying there’s only one star in New York bigger and badder than Jay-Z, and that’s Robert De Niro.