1. dig up dirt - Verb
2. dig up dirt - Phrase
dig up dirt (third-person singular simple present digs up dirt, present participle digging up dirt, simple past and past participle dug up dirt)
(idiomatic, usually with on) To examine in order to find negative information for public opinion, usually with the purpose of embarrassing or discrediting a person.
The freelance investigative reporter made a career of digging up dirt on celebrities for tabloids.