AceShowbiz -

What happened with Sean Penn? The "Milk" actor was caught on camera going ballistic on his daughter Dylan Frances Penn's boyfriend, Jimmy Giannopoulos, on May 30. At the time, Sean, Jimmy and Robin Wright enjoyed a quiet dinner at Le Gamin in Brooklyn before they went outside.

In some photos obtained by Radar Online, the three huddled on a nearby stoop. Sean crouched in front of them before he inexplicably exploded, prompting his ex-wife Robin to burst into tears.

An eyewitness reveals, "Sean had his cell phone in his hand and held it up to Jimmy's face to show him the screen. A heated exchange followed, and Sean's face got redder and redder as he confronted Jimmy with whatever was on the phone."

Soon after, Sean began yelling at Jimmy and pointing at him angrily. "At one point, Robin broke down in tears, and Sean comforted her with a hug and held her hand. Eventually, all three calmed down, and someone met them on the sidewalk, carrying their luggage," adds the source.

According to the source, Sean and Robin, however, later parted on friendly terms Jimmy. "Things seemed to have ended amicably, as the trio hugged before going their separate ways," says the source.

A representative for Sean hasn't responded to a request for comment.