The face is an important part of the body. It was Helen of Troy’s face that launched a million ships. What is lesser known is that the face has also contributed many idioms to the English language.
Staring someone in the face: very obvious or clearly noticeable, but often not noticed by the person concerned.
I spent hours wondering who I could turn to for help in finishing my school project, while the answer was staring me in the face all the time.
Long face: sad look.
When I told my son that we could not go for the movie, he pulled a long face.
Slap in the face: action that insults or upsets someone.
The decision to freeze salaries was a slap in the face of the employees who had for long campaigned for an increase in pay.
As plain as the nose on your face: be very obvious.
I knew he was lying. It was as obvious as the nose on his face.
In your face: shocking or annoying in a way that is difficult to ignore.
Films being made these days are bold, brazen and in your face.
Written all over someone’s face: an emotion that is clearly visible on someone’s face.
I know he is in love with her. It is written all over his face.
Blow up in someone’s face: (used of a plan or arrangement, etc) has a bad effect on someone instead of the results they expected.
The university’s plan to change admission rules blew up in its face, with the students accusing the university of unfairness.
Come face to face with someone: suddenly meet someone by chance.
Sparks are expected to fly when the presidential candidates come face to face for a public debate.
International Dictionary of Idioms)