She raised her voice at a taxi driver who asked for directions and flew into a rage when he told her to stop being rude.
Beer promoter Huang Jia Jia, now 27, even smacked cabby Mok Sook Sheng multiple times while he was driving.
He was forced to pull over as he did not want to endanger other road users.
Huang, a Chinese national, was yesterday jailed for three weeks after she pleaded guilty to one count each of committing a rash act and causing hurt.
When she boarded Mr Mok's taxi near Lorong 25A Geylang at around 9.40pm on July 10 last year, Mr Mok noticed that she was intoxicated and her breath was reeking of alcohol as she sat in a rear passenger seat, the court heard.
When they reached Circuit Road, the cabby asked her for directions to her destination.
She raised her voice and replied: "Go straight... I can pay the fare, just go."
Deputy Public Prosecutor Andre Chong said: "The victim told the accused that she did not need to speak so loudly as she was in close proximity to him. He also asked her to talk nicely and not to be rude."
When she heard this, she began slapping the cabby's head and face several times.
Mr Mok, who was still driving the taxi, tried to dodge the blows but failed.
He was forced to reach behind him with his left hand to deflect her blows while using his right hand to steer the vehicle.
He also asked her to stop but his request fell on deaf ears and she continued hitting him.
"Fearing that other road users might be endangered, the victim brought the vehicle to a stop by the side of the road," said DPP Chong.
Mr Mok told Huang that he would be alerting the police. She responded by smacking his head one more time. Officers soon arrived at the scene and arrested her.
DPP Chong urged District Judge Brenda Tan to jail Huang for at least three weeks as she had been violent towards a public service worker.
Her lawyer, Mr Wee Hong Shern, pleaded for either a high fine or a three-week jail term.
He said there had been a misunderstanding and his client had raised her voice as she was then wearing her earphones.
For committing the rash act, Huang could have been jailed for up to six months and fined up to $2,500.
And for causing hurt to Mr Mok, she could have been jailed for up to two years and fined up to $5,000.