A full-time national serviceman with the Singapore Civil Defence Force fell out of a car after he went to a bar in Sentosa with his friends last Saturday night.
The 23-year-old man, identified only as Mr Eddy, lay on the road with serious head injuries until the police arrived.
He died in hospital about a day later.
Three full-time national servicemen, all in their 20s, have been arrested for allegedly causing his death through a rash act.
It is believed they were in a Mercedes convertible and visiting a bar owned by the father of one of the men.
Mr Eddy's friends were at the scene when the police arrived on Sentosa Gateway, after receiving a call at about 2am.
His childhood friend and neighbour said Mr Eddy had told him he was going out with his camp mates that night.
The friend, who did not give Mr Eddy's full name as he said he was not authorised by the family to do so, said Mr Eddy seldom went out with his camp mates.
He said he rushed to the hospital after Mr Eddy's family called him.
The friend, who declined to be named, said they were told by the hospital that Mr Eddy had very little chance of survival.
The Singapore Civil Defence Force said that when paramedics arrived, Mr Eddy was not breathing and had no pulse, but was revived en route to the hospital.
He was on life support for a day, during which he had some 200 visitors, said the childhood friend.
Mr Eddy had ambitions of becoming a businessman.
"He was one of the best people in the world. He was happy-go-lucky, popular, funny," the friend said.
His corneas and kidneys were donated after his death.
Mr Eddy's friend added that he would miss his pal, whom he saw nearly every day.
He said: "When he was by my side, he gave me confidence. It's hard to accept he is gone."
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