In the tunnel running between Sham Shui Po and Shek Kip Mei, there is an old man who plays music every morning. When there is construction work inside the tunnel, the two sounds form a duet, without suppressing one another.

往來深水埗和石峽尾的隧道中，有位伯伯每天早上都在彈奏樂曲；碰巧遇上工人在隧道內進行工程，兩種完全不同的聲音展開了二重奏，不分高下。