When you encounter someone who is inexperienced in working around language issues, it can be very intimidating even for the “expert” language learner.
“Wo ist ___ Treppenhaus?” I scramble to think. Is Haus der, dir, oder das. Who cares. What is a Treppenhaus? Is it a building? A different type of place? Where is the Treppenhaus? How do I get to the Treppenhaus via the Lift (elevator). Supposedly the Treppenhaus is something like 1/2 a flight above me. How can a building be on half of a floor.
When pressed for understanding, the speaker likely feels as desparate as you do to understand. Maybe she too is thinking of the Treppenhaus tonight.
Short story longer, when I did not understand and failed to figure out where the Treppenhaus was, I went back to the counter to write down the step-by-step instructions. I wrote:
I decided to leave and come back tomorrow because I was shaking with stress. German interlocutors (speech partners) can be brutal on the physche. Gather your wits and try again tomorrow.
When faced with an unknown word under pressure, remember that you can ask a couple of clarifying questions:
If nothing else, these questions let the speaker know for certain that you are lacking this vocabulary word and seek to understand it.