The one that got a few of the nurses when we were applying for the critical care fellowship was "your patient is post op 2 hours. His blood pressure is 75/40. What would you do first?" Almost everyone said "call the doctor". They were looking for a more "critical care" answer such as "how are you getting the pressure, via a manual cuff, dynamap, or arterial line?" Also, they wanted to know if the patient was stable, what their heart rate was doing...stuff like that. They want to make sure that you see the BIG PICTURE of your patient, and not just the fact that their pressure is low.