take into head
take (something) into (one's) head
To believe that something is true. Take 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 taken it into his head that holding his breath will make him taller."
take something into one's head
Fig. to get an obsession or overpowering idea into one's thinking. George took this strange idea into his head about fixing the car himself. I don't know why she took that strange idea into her head.