Pour full-strength, undiluted white vinegar onto grass that you want to kill. This works well in areas like sidewalk crevices and driveways where grass roots are hard to reach with your hands.
Vinegar is a natural solution that will not leave undesirable residue in the area or cause problems if it is washed out into the waterways.
Vinegar is not a selective herbicide, and it will cause other plants to wither and die as well.
You may also pour distilled white vinegar onto anthills to kill ants. Similarly, make up a solution that is half white vinegar and half water, put it in a spray bottle, and use it to kill slugs. You can also use it to take out water stains in the carpet.