He's known for his sharp wit and aggressive questioning style. It's possible the phrase you're thinking of is something similar, or perhaps a combination of lines from different episodes.
To help me find the specific episode you're looking for, could you provide some more context?
* What is the general situation in the episode? (e.g., a murder trial, a high-profile case, etc.)
* Who is Jack McCoy talking to? (e.g., the defendant, a witness, another lawyer)
* What is the general tone of the scene? (e.g., confrontational, sarcastic, humorous)
With more information, I might be able to track down the specific episode you're thinking of.