Dr. Vittorio Sacerdoti worked in a small hospital on an island in the River Tiber. He lived in the Jewish ghetto during the war and was terrified when the Nazis arrived and started to haul away his fellow Jews. He came up with a fake disease which he named “K Syndrome” - named after the German commander, Kesselring. He admitted as many Jews to his hospital as he could and diagnosed them with “K Syndrome.”
“At the moment when we had to say what disease they suffered? It was Syndrome K, meaning ‘I am admitting a Jew,’ as if he or she were ill, but they were all healthy” — Dr Ossicini
The doctors instructed “patients” to cough very loudly and told Nazis that the disease was extremely dangerous, disfiguring and very contagious. Soldiers were so alarmed by the list of symptoms and incessant coughing that they left without inspecting the patients.
Edit:
A small correction, the man in the pic above is Giovanni Borromeo. Both Sacerdoti and Borromeo came up with a plan to diagnose the refugees with a fictitious disease. And the name Syndrome K came from Dr. Adriano Ossicini, an anti-Fascist physician working at the hospital.