They drank, danced and made merry. It would have been a night to remember for all the right reasons, until three Kampong Thom youths ditched the festivities to settle an old score.
Last month, the youngsters had argued with another gang, and on Sunday one of them happened upon their night out by chance.
The trio gave chase and beat the 18-year-old to a pulp with their belts.
Police made arrests, discovering they arrived just in time, as the gang had two long swords stashed in their motorbikes for just such an occasion.