noun
takenoko nyokki; bamboo shoot game
A group party game where players put their hands together and try to raise them while saying 'nyokki' in turn, without speaking over each other. The last player remaining is the loser. The name is often written in kana.
飲み会で竹の子にょっきをして盛り上がった。
We got excited playing takenoko nyokki at the drinking party.
竹の子にょっきのルールは簡単だけど、つい声が重なってしまう。
The rules of takenoko nyokki are simple, but you end up speaking over someone.
From 竹の子 (bamboo shoot) and the onomatopoeic にょっき (something sprouting up). The game's name evokes bamboo shoots popping up one after another.