The teens, all juveniles, were arrested and charged with "uttering a forged document" with two also facing charges of theft by deception. Investigators say they produced about $1,000 worth of counterfeit money and used it to buy snacks at Dunkin' Donuts and 7-11.
School Superintendent Michael Polizzi said there could be "pretty severe suspensions" because one bill was passed in the high school cafeteria.
"I don't think they fully realized they were committing a crime against the United States government," Police Chief Frank Papapietro told NorthJersey.com Thursday.
When U.S. Secret Service agents showed up, it was a "real wake-up call" for the students, the chief added. Papapietro said the operation was amateurish with the printing done on resume paper using an ink-jet printer.
Papapietro said the teens have been charged as juveniles and are unlikely to do time.
Joe LaSorsa, a retired Secret Service agent, told NorthJersey.com that inexperienced counterfeiters are usually caught quickly because their bills are easy to detect and generally passed in a small area.
"They do it just enough to get in trouble," LaSorsa said. "I don't think anybody is getting rich doing this."
New Milford is an affluent New York City suburb. Other high school students described the counterfeiting as stupid.