land mine

noun4

1. •
   A mine that is placed on land and designed to explode when stepped upon or touched.
2. •
   (figurative) A critical subject or situation with concealed or unpredictable implications.
3. •
   (slang, figurative) A pile of uncollected dog feces that has been left on a public area (such as a sidewalk, park, or common lawn) and on which someone might accidentally step.

   • Our streets and sidewalks have been overrun with trash, and the dog feces landmines that pedestrians have to navigate are an added element having deleterious effects on our health and well-being ... — 2022
4. •
   A piece of exercise device consisting of a pivoting tube attached to the ground to which a barbell can be fitted to lift it off the ground.