He received a message from an Instagram account he thought was his friend's, as the username and picture were similar.
Wanting to be known only as Mr Meng, 21, he said in an interview with the police that the "friend" said she had entered a contest organised by Grab and needed votes from her friends.
She asked Mr Meng for his phone number, and he was told to share the one-time password provided by Grab to cast as "votes".
To his surprise, he discovered the fraudster had gained access to his GrabPay account and used $390.80 to purchase credits on a gaming website.
He called his friend to clarify the incident and realised he had been scammed.
A similar tactic was used on five other impersonation victims The New Paper contacted.
Police told TNP that reports of social media impersonation scams have been on the rise, with more than 206 reports made last month.
These scams were the fourth most common type last year, with 810 cases reported, 703 cases more than 2018.
More than $3.1 million was lost last year from these scams, including the largest case involving $330,000.
The police said these fraudsters often used compromised or spoofed social media accounts to deceive the victims.
Miss Grace Cai, 21, a Singaporean studying at the University of Melbourne, said her friends were similarly asked for their numbers by an account that looked like hers. They were told about a promotion they could redeem.
She said: "I put out an Instagram post about the fake account and warned my friends not to give (out) any details."
However, Miss Cai said a few friends gave their numbers.
"Hopefully nothing happens next," she said, adding that she set her account to private after the incident.
The police said these fraudsters usually ask for details such as mobile numbers, banking details and one-time passwords, with reasons such as signing up for contests or promotions.
Members of the public are advised to be wary of unexpected requests on social media and verify the legitimacy of the account by checking with friends or family offline.
To provide information on such scams, go to police.gov.sg/iwitness or call 1800-255-0000.
This article was first published in The New Paper. Permission required for reproduction.