In the abandoned St Marks School, Shau Kei Wan, Hong Kong.
小心D means be careful
有 means have
鬼 means ghost
so 小心D 有鬼 means "Be careful. There are ghosts."
I had been here once before, months ago, so imagine my surprise to discover that my chalkboard graffiti in the Physics lab was still intact. But just what "#" is Elyse Sewell? Wouldn't you like to know!