Others will use your eight-character idiom.

Explanation: mustard: grass. As light as dirt and grass. Metaphor is extreme contempt.

Said by: "Mencius Li Lou": "If the monarch and his subjects are like dirt, then I regard you as my enemy."

Ex.: Let him live and let him die. ◎ Lu Xun's essays on the pavilion after illness.

Synonym: treating me like a shoe, ignoring human life and dismissing it.

Antonym: Be impressed and cherish yourself.

Grammar: complementarity; As a predicate; derogatory sense