using one's hand as a plate
Describes the act of cupping one's hand under food to catch drips or crumbs, often while eating something messy. Common in everyday conversation.
When eating a rice ball, using your hand as a plate is convenient because it prevents spills.
He unconsciously cupped his hand under the cookie while eating it.
Compound of 手 (hand) and 皿 (plate). The exact origin is uncertain, but it likely arose from the visual similarity of a cupped hand to a small plate.