noun
pledge over sake cups; exchange of nuptial cups
Refers to a traditional ritual where sake cups are exchanged to seal a bond, most commonly in wedding ceremonies (san-san-kudo) or formal pledges.
結婚式で杯事を行う。
They perform the exchange of nuptial cups at the wedding ceremony.
杯事を交わして兄弟の契りを結んだ。
They exchanged sake cups and swore a brotherly bond.
Compound of 杯 (sakazuki, 'sake cup') and 事 (koto, 'matter/ritual'), with rendaku voicing of koto to goto. The exact historical origin is uncertain, but it has long been associated with ceremonial sake drinking to seal agreements or marriages.