bachelor party
US /ˈbætʃ.əl.ər ˌpɑːr.t̬i/
UK /ˈbætʃ.əl.ər ˌpɑːr.t̬i/

1.
a party for a man who is about to get married, attended by his male friends
:
•
We're planning a wild bachelor party for John next month.
•
The groom's friends organized a surprise bachelor party.