kaku-tto
A sudden loss of strength in the knees or neck, causing the body to jerk downward. Often from exhaustion or falling asleep.
💡Dozing off on the train — 'My head dropped kaku-tto and I woke up startled.'
電車で居眠りして、首がかくっとなった。
I dozed off on the train and my head dropped kaku-tto.
My legs went ___ after running the marathon.
マラソンの後、膝が○○となった。