This is one of my favorite lines. It manages to express the feeling of troubles stacking up relentlessly as they do tend to do, while simultaneously personifying that trouble in an almost whimsical way. I see the woes as bedraggled soldiers walking along a dusty road and they keep giving each other flat tires by stepping on each other’s heels. And the one who has been trod upon looks back at the trodder and gives him a steady glare and a fist shake, as well as a few choice swear words. The trodder apologizes, tries to ingratiate himself to the one he’s stepped upon and is very shortly trod upon himself by the man behind him.