Also:
hurl mud
throw mud
Meaning of Idiom ‘Fling Mud’
To make disparaging or shocking remarks about someone; to criticize someone in an attempt to damage their reputation.
Usage Notes
Also used as a noun, mud-slinging.
Examples Of Use
“The candidates are too busy slinging mud to talk about the issues.”
“The celebrities are involved in a contentious divorce and have been slinging mud at each other in the press.”
Origin
This idiom has its origin in a 15th-century proverb attributed to Florentine statesman Niccolo Machiavelli:
“Throw dirt (or mud) enough, and some will stick.”
