stand there with one's bare face hanging out

stand there with one's bare face hanging out: "

stand there with one's bare face hanging out (to stand some place looking helpless and stupid) — (стоять) как дурак, с идиотским / глупым выражением лица

Don't just stand there with your bare face hanging out. Say something. (thefreedictionary.com) — Да не стой ты как идиот. Скажи что-нибудь.