Singer Boy George has been warned he will be jailed unless he completes five days of community service in New York before the end of August.
O'Dowd was sentenced in March after falsely reporting a burglary
The star - real name George O'Dowd - appeared before Manhattan Criminal Court after failing to begin a sentence for wasting police time.
Judge Anthony Ferrara did not reveal the form of O'Dowd's punishment.
But O'Dowd's manager Jeremy Pearce confirmed that the star would be picking up leaves in a New York park.
The judge told the former Culture Club star the community service should be "a simple matter".
"It's up to you as to whether it will be an exercise in humiliation or an exercise in humility," he said.
Pointing to the courtroom's exit, he told O'Dowd, 45: "If you do community service, you go out that door."
Then he threatened a spell in prison, by saying: "I'm going to make you a promise. If you don't do this community service, you go through the back door."
Culture Club's single Karma Chameleon, released in 1983, sold more than 1m copies
Judge Ferrara warned: "I'm not going to give you another chance."
O'Dowd had pleaded guilty to falsely reporting a burglary at his home in Lower Manhattan last October.
Under a plea deal, he was sentenced to complete a drugs programme in the UK, along with the community service in New York.
"I don't care about doing cleaning up. My mum was a cleaner," O'Dowd told the Press Assocation afterwards.
"I was worried I would have to wear an orange boiler suit, but apparently I can wear what I like. I'm going to dress up - I'll wear something loud."
O'Dowd added his arrest had been "just a very unfortunate trauma".
Earlier this month, Judge Ferrara ridiculed the star for asking if he could stage a fashion and make-up workshop as part of his sentence.
However, his lawyer had maintained that O'Dowd hoped to do something other than sweeping pavements.
"There's nothing wrong with that if that's part of his punishment, but it will turn into a media circus, and the press will be following him every day," Mr Freeman had warned.
O'Dowd has until 28 August to complete his community service.