A man walks by himself and watches the fine ladies around him, humming quietly as if to keep himself company. Then the poem turns sharply. He admits he fears he is dead, and the place he locates that fear is "under my clothes," in the body itself.
The contrast is what stings. The ladies are elegant, presumably full of life and noticed by the world, while the speaker is unseen and cut off. His humming sounds like a small, private way of proving he's still here. The idea of clothes is striking too: they suggest outward appearance, the respectable surface a person shows, while underneath he feels empty or lifeless. The title, "Walking dead," makes the image even stranger, a body still moving but without real life in it.
The mood is lonely, hushed and a little eerie. The short lines and plain wording make the confession feel quiet and honest rather than dramatic, which makes it hit harder.