a deer in the headlights

(be caught/freeze like) a deer in the ˈheadlights

(also (be caught like) a rabbit in the ˈheadlights) used to describe somebody who appears so frightened that they cannot think clearly and do not know what to do or say: The senator was caught like a deer in the headlights in a TV interview.a deer-in-the-headlights look
See also: deer, headlight