trick sake cup that cannot be set down until empty
A traditional drinking vessel designed with a hole or shape that forces the drinker to finish the sake before putting the cup down. Often used at parties or ceremonies.
At the party, trick sake cups were brought out and everyone downed their drinks in one go.
Alternate kanji spelling using the kana べく for the first part.
The name alludes to the kanbun reading of 可 as べく: 可 must be followed by another word and cannot end a sentence, just as this pointed or otherwise unstable cup cannot be set down before it is emptied.