おやのすねをかじる
oyano suneo kajiru

Godan Verb (ru)
Idiomatic Expression

1. to depend on one's parents' (financial) support; to nibble at one's parents' shins — literal

かれはまだ おやのすねをかじっている。
karewa mada oyano suneo kajitte iru.
He's still sponging off his parents.
Other forms: