Devil's strip

Definition:
The name of the strip of grass between the sidewalk (the paved strip for people to walk on) and the street (where motorized vehicles run).
Update : In Australia it's called a Nature Strip.

Usage:
He mowed the lawn but forgot to do the devil's strip.

Explanation:
Not a clue! I grew up in that town and nobody I've met has a clue!
In Australia it's called a Nature Strip