1
general::
Phrase(s): do a job on someone or something
1. Euph. to defecate on someone or something. (Note the variation in the second example.) • The puppy did a job on the living-room carpet. • It’s supposed to do its job on the newspapers in the basement. 2. Sl. to damage someone or something; to mess up someone or something. • The robbers really did a job on the bank guard. They beat him when they robbed the bank. • The puppy did a job on my shoes. They are all chewed to pieces.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Also, do a number on. Damage, harm, as in The cat really did a job on the upholstery, or The teacher did a number on the class with that assignment. This slangy idiom uses job (or number) in the sense of "something negative."
American Heritage Idioms