“I have a gun. Give me $40,” the would-be Long Island bank robber’s note said.

But his intended victim, a female teller at the HSBC branch in West Hempstead, disarmed him with just four words:

“Are you for real?”

Taken aback, the robber “nodded his head yes, but she basically just didn’t react. He took his note and left,” said Nassau County Police Detective Sgt. Gary Schriffen.

The request for such a specific, small sum was unusual, Schriffen said. “We don’t usually have people asking for specific amounts.”

The weak-willed bad guy was described as being in his early 20s, wearing a dark baseball cap and a blue windbreaker.

Anyone with information about the Thursday robbery attempt is asked to call Crimestoppers at (800) 244-TIPS.

Meanwhile, Schriffen’s robbery squad busted a 48-year-old Bronx man with a history of bank robberies on charges of robbing two banks of more than $10,000.

Anthony Saciolo, 38, of 1577 Paulding Ave. in The Bronx, was arrested after he was captured on a bank security video that was publicized. A tipster who recognized Saciolo called police, Schriffen said.

Schriffen said Saciolo robbed a North Fork Bank in Farmingdale, L.I., on Tuesday at gunpoint and also stuck up a Fleet Bank branch in Baldwin, L.I., last month. A pellet gun believed to have been used in the robberies was recovered.

Saciolo is also expected to be charged with a robbery at another Fleet Bank branch, in Suffolk County, Schriffen said.

Sources said Saciolo was arrested in 1990 for a series of five bank jobs in Nassau County - also after he was caught by surveillance cameras and identified. He was sentenced to a 5-to-10-year prison stretch for those crimes.

Saciolo was also briefly embroiled in the case of Long Island Lolita Amy Fisher.

But Saciolo later denied signing an affidavit that branded Joey Buttafuoco a pimp and drug dealer.