When a six-foot man strode into a Long Island bank yesterday dressed as sci-fi super villain Darth Vader, customers and staff thought it was a joke.
But they soon realised how serious the man was when he produced a handgun and demanded cash.
Police in New York are now trying to trace the phantom menace, who stuffed cash into a bag and disappeared.
The man entered the Chase Bank in East Setauket around 11:30am, wearing the distinctive Darth Vader mask, a long black cloak and - slightly out of character - camouflage combat trousers.
One customer thought the outfit was so funny that he started joking with the dark lord as he tried to pull off his heist.
Suffolk County Police Detective Sergeant William Lamb said: 'The customer thought it might have been a joke, and not a serious attempt at a robbery.'
But staff and customers were left in no doubt when the man then produced a handgun from a bag and screamed, 'This is not a joke' to cashiers.
Police have released CCTV images of the man stuffing the money into a drawstring bag featuring a New York Yankees logo.
As he left the robber punched another customer who tried to stop him.
The bank was still checking its drawers last night to figure out how large his take was, Detective Lamb said.
It was the second recent off-the-wall bank robbery. On Wednesday, the NYPD arrested a man dubbed the 'Bouquet Bandit', who acquired his unusual nickname after bringing flowers and potted plants into the banks he robbed.