get (something) into (one's) head

get (something) into (one's) head

To believe that something is true. Get it into your head: I'm in charge until Mom gets home, so you have to listen to me. A: "Why is Johnny holding his breath?" B: "Well, he's gotten it into his head that holding his breath will make him taller."

See also: get, head

get something into your/somebody’s (thick) ˈhead

(informal) succeed in understanding or in making somebody understand something fully: When are you going to get it into your thick head that you don’t need to worry about money? You’re rich now. ♢ I’m still trying to get it into my head that I’m free to do what I want now.

See also: get, head, something