dastehen wie der Ochs vorm Berg
to stand there helplessly/cluelessly, not knowing what to do
Origin
Comes from vivid rural language: the heavy, sluggish ox stops helplessly before an obstacle and doesn't know how to go on. The expression is old and was already used by Luther; there are variants such as 'in front of the barn door'.
Building blocks
Words in this expression
Examples
Als der ihn der fragte, stand er da wie der Ochs .
When the teacher asked him for the answer, he just stood there like a deer in the headlights.