A girl aged only 15 was "morally corrupted" by a man she met online and went on to have sex with him and others.
Chee Wei Tong, 24, a former customer service officer with Coca-Cola Singapore, was jailed for 30 months yesterday.
It was the stiffest sentence to be handed down compared with three other men who were convicted and jailed between 10 and 12 months each for having sex with the minor.
A fifth man's case is pending.
Chee, also a grassroots volunteer at Punggol 21 community centre, had admitted to three charges and had seven others taken into consideration.
District Judge Hamidah Ibrahim noted that the girl went on to have sex with four other men after Chee. She agreed with the prosecution that Chee had morally corrupted the girl.
She also agreed with the prosecution that there had been aggravating factors.
He got to know the girl in mid-2012 when she created an account on OkCupid, a dating and social networking website. In the course of texting, she told him she was only 15 years old. He told her that he had a girlfriend but practised polyamory - being romantically involved with several individuals at the same time.