Life In The City . . .

. . . sometimes involves getting mugged at the movie theater:

A nanny and the 5-year-old son of an investment banker — enjoying an action flick at an Upper West Side multiplex — got a harrowing dose of real-life terror when a gunman robbed them in the darkened theater, the victim told The Post.

“It’s either your life or the little boy’s life,” the bandit told Marzena Drus, 27, as she clutched Nicholas Anzivino on her lap, she said.

The shocking incident happened during a showing of “Speed Racer” at Loews Lincoln Square on Broadway at West 68th Street Tuesday afternoon, the nanny said.

“It was an action part and [Nicholas] was into the movie,” she said.

“Someone comes behind me and points a gun at me and says, ‘Hand me the purse!’ I said, ‘No!’ ”

The feisty Drus said the thief just reached over her and Nicholas and grabbed her purse.

“I had the gun pointed at my head,” she said. “Then he grabbed my purse and left.”

A theater manager recovered Drus’ empty purse nearby and offered her two free tickets.

Nicholas’ mom, Stephanie Anzivino, an investment banker at Merrill Lynch, was incensed.

“It seems highly irresponsible, to put it mildly, to have someone running around in a theater with a gun and not to try to do something,” she said.