Stroppy Sean Penn was involved in a foul-mouthed bust-up with a fan on Tuesday (19Nov13) after he spotted the man trying to take a sneaky cell phone photo of him.

The Milk star was chatting with friends at a bar in the St. Regis Hotel in San Francisco, California but he suddenly exploded when a camera flash went off.

Penn saw an unidentified man several yards away trying to snap him on a cell phone, and he angrily confronted the fan, ordering him to leave the bar.

In dramatic film footage obtained by, Penn is seen saying to the man, "Get the f**k out of here - I'll make you eat the phone," but when he refuses to move, the actor points to the exit and shouts, "Get out of here!"

Seconds later Penn is seen apparently complaining about the incident to hotel staff, saying, "You guys should do something about that."

Penn was reportedly in San Francisco to speak at a sales conference.