What do you mean you don't understand? It's as plain as the nose on your face.Your guilt is plain as the nose on your face.
(redirected from plain as the nose on one's face)
(as) plain as the nose on (one's) face
Very obvious or noticeable. Those two have been flirting all afternoon—it's as plain as the nose on your face!In the end, the solution was as plain as the nose on my face.