寝首 ねくびをかく
nekubio kaku

Godan Verb (ku)
Expression

1. to cut off the head of a sleeping person; to assassinate someone while they sleep

いつ寝首 ねくび かれるかわかったものではありません。
itsunekubio kakareruka wakatta monodewārimasen.
There's no telling when she'll stab you in the back.
Godan Verb (ku)
Expression

2. to catch someone off their guard by setting traps

Other forms: