take it into your 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."
See also: head, take

take it into (one's) head (to do something)

To decide or become set on the idea to do something, often something capricious. Jane has taken it into her head to become a glassblower, and she's already ordered all the tools.
See also: head, take

take it into your head

If somebody takes it into their head to do something, especially something strange or foolish, they suddenly decide to do it. He suddenly took it into his head to go out to Australia to stay with his son.
See also: head, take