What song does Trevor Poe play to let his friends know he is in the house?

Sheba Poe returns to Charleston to enlist the help of her former classmates in tracking down her brother Trevor. It's a sign of how close the members of the group are that they gladly accompany Sheba to San Francisco, where it's thought that Trevor might be staying. Apparently, Trevor is in a bad way, close to death from the AIDS virus. So it's all the more imperative that he's found as soon as possible.
After a long, eventful journey, the friends are led to a dilapidated old Victorian house. A racist homophobe by the name of Bunny claims that he lives there alone. But his insistence is belied by the piano music emanating from deep inside the house. The distinctive strains of "Lili Marlene" drift gently out of the window, immediately alerting Sheba and her friends to Trevor's presence inside the building.
"Lili Marlene" is an old wartime song, and it has especial significance for Trevor and Sheba. In high school they entered a talent contest, and their rendition of the song won first prize. It was the talk of the town for weeks.