An idiom meaning to depend financially on someone else (usually one's parents), i.e. to live off them rather than being independent.
大学卒業してもすぐに就職せず、親のすねをかじる若者がいる。
There are young people who, even after graduating from university, don't get a job right away and live off their parents.
いい年をして親のすねをかじるのはやめなさいと言われた。
I was told to stop depending on my parents at my age.
彼は働き始めてから親のすねをかじらなくなった。
After he started working, he stopped living off his parents.