with rice stuck on one's face
Jocular, idiomatic expression used as a tease when someone has rice stuck on their face, often in the question お弁当つけてどこ行くの？ (Where are you going with your lunchbox on your face?).
You've got a grain of rice on your face. Where are you going with your lunchbox on?
Alternate spelling using 付ける; less common but attested.
A playful phrase combining お弁当 (lunchbox) and つけて (attached), humorously likening a rice grain stuck on the face to carrying a lunchbox.