paka-tto
Something splitting open neatly — an egg hatching, a shell cracking open, or a lid popping off.
💡A chick hatching from an egg — 'The egg went paka-tto and a tiny beak appeared.'
卵がぱかっと割れてヒヨコが出てきた。
The egg cracked open paka-tto and a chick appeared.
The egg ___ split open and a tiny chick emerged.
卵が○○と割れて小さなヒヨコが顔を出した。