using one's head

Verb

use one's head (third-person singular simple present uses one's head, present participle using one's head, simple past and past participle used one's head)

1. (idiomatic) To think carefully, especially as an alternative to being guided by one's emotions.
   • He never—so they agreed—uses his head. He never—I think I have their phrase correct—stops to think.1918, Stephen Leacock, “Back from the Land”, in Frenzied Fiction

   Synonyms:

   use one's noggin, use one's coconut

2. (humorous) To headbutt.