use one's head

use one's head or  {slang} use one's bean or  {slang} use one's noodle or  {slang} use one's noggin  {v. phr.}
To use your brain or mind; think; have common sense. — Often used as a command.
If you used your bean you wouldn't be in trouble now.
Never point a gun at anybody, John. Use your head!
Categories: slang verb