While it was supposed to be a celebration for Leonardo DiCaprio’s 38th, for Jay Z and Robert De Niro it was far from that. Supposedly, everything went south when Jay Z said hello to the legendary actor.

Get Informed withthe details, after the jump!

via NY POST

”Bob was sitting at a table, and when Jay-Z went over to say hello, De Niro told Jay that he never called him back.

”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.”

The argument was over a song Jay-Z had agreed to record for the Tribeca Film Festival, but the superstar rapper never got back to fellow Tribeca resident Robert with details about the track.

Jay-Z’s wife Beyonce Knowles – with whom he has 10-month-old daughter Blue Ivy Carter – attempted to diffuse the situation, but onlookers were amazed to see ”scary” Robert put the rap star in his place.

The insider added: ”When Jay-Z tried to make a joke of it, saying he is terrible on the phone, De Niro kept telling him that he thinks he’s the man, but that he was disrespectful.

”Beyonce 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. He can be quite scary when he’s angry.”