Fig. to strike a person hard on the skull as if to knock out the person's brains. (Often said as a vain threat.) I thought he was going to brain me, but he only hit me on the shoulder.If you don't do it, I'll brain you.
brain
1. n. a good student; a very intelligent person. (see also brains.) I’m no brain, but I get good grades.
2. tv. to hit someone (in the head). I ought to brain you for that!