Season 2 Episode 8 has a good one from a college student. Mike Logan asks a question which is quite offensive and the rebuttal of the student is simple brilliant. "Does they give you guys insensitivity-seninars?" Before she continues to explain,.
Season 6, Episode 11, "Corpus Delicti": Jack deliberately disobeys a judge so as to provoke a mistrial. The case was highly circumstantial and he didn't want the suspect to walk. A few weeks later, physical evidence turns up, allowing Jack to try the case successfully. Of course, if the defense can prove he deliberately provoked a mistrial for this purpose, he could be disbarred. Deadpan, Jack says, "It wasn't like that at all. You know how emotional I get."
From the same episode: Lennie's inspired impersonation of Mister Ed.
Season 11, Episode 13, "Phobia": A man has been murdered, his baby kidnapped, a ransom demand phoned in. The cops follow a bike messenger and then rush in, grabbing the messenger and the man he's giving the ransom to. Turns out the ransomer had already left and it was just a random guy. His wife comes out of the coffee shop holding a pair of lattes and sees him handcuffed and surrounded by cops, guns drawn. "I told you not to double park."
Season 18. Episode 11, "Betrayed": Fueled by a dose of Mood Whiplash. Ed 'reads' a suspect her medical record, causing her to freak out and confess to the murder. When confronted by Lt. Van Buren that reading her medical file was illegal, Ed reveals the 'file' to be a signup sheet for a blood drive, a sketch for the suspect of a peeping case and take-out menus.
In one later season episode, the cops find that a victim's body has been cremated and his ashes have been incorporated into an artificial gem. Desperately, they go to The Coroner and ask if there is anything she can tell from it. At that, she holds the gem and wryly notes, "Well, he has many facets."
Season 10. Briscoe. "If I was kidding you, I'd be wearing a fez and no pants."
Season 7, Episode 7 ("Deadbeat"): Lennie getting hit on by an old woman. Curtis points out the woman's attraction as they leave. Lennie states that he should play his cards right.
One scene where Briscoe's watching a bunch of crime-scene techs dumpster-dive in order to find some evidence.
Tech: You know, last time we had to go through the trash, the investigating officers helped out. Briscoe:[Clearly with no intention of helping out] That's fascinating. I think you missed a spot.
14x09 "Compassion": During a discussion with a laboratory doctor, he picks up a test rabbit and moves it to another cage. Ed Green then sticks his finger through the bars to try and pet the rabbit and the doctor slaps his hand to stop him while continuing to talk as though nothing is happening.
Season 14, Episode 1 ("Bodies"): a legal aid defense attorney takes on a serial killer, and DA Branch has a... less than favorable opinion of him.
DA Arthur Branch: Who is that stupid SOB anyway?
ADA Serena Southerland: Ken Schwimmer, Legal Aid, and he isn't exactly stupid.
Arthur: He listened when his client told him about fifteen other murders?
7x19: "Double Down": A defendant tries to hide behind a deal he forced McCoy to take, but when McCoy found the deal was a trick the whole time, he tries to circumvent the deal while keeping the information the defendant gave him. During an evidentiary hearing, Curtis was asked why McCoy didn't realize that the defendant's partner was killed by the defendant, despite it being the logical explanation for a district attorney to come up with. Curtis's reply was "For a cop? Sure. For a DA? I've found sometimes they're not all that bright." Even McCoy was amused at this backhanded reply. When the hearing leads to allowing the defendant to be tried, Curtis asks McCoy, "What would have happened if I had told them you told us to shut up?" McCoy's reply: "It would have hurt. Hey, look at it this way. At least you got to duck the question by calling me an idiot." Curtis grinned. "Yeah. There is that."
A slightly morbid example in "Cradle to Grave" 2x18. A horrid landlady blames the rent laws for her pushing out tenants, leading to the death of a 10-month-old baby. She then starts heavily implying that an important witness will soon change his mind, to Stone's utter disbelief... with her lawyer trying to get her out of the room and shut her up while saying none it counts. It's better watched.
When getting evidence with Robinette, the undercover cop gets stuck in traffic. With time running short, Logan gets Robinette to change jackets with him (the man had already seen the cops and would recognize them). After Robinette gets the evidence, Logan immediately demands his jacket back.
After dealing with nearly a whole episode's worth of witnesses completely unable to describe the suspect, Lennie and Mike Logan are questioning an old black couple. The wife can't describe the suspect either and both detectives are nearly at wit's end...when she reveals she did neighborhood watch training and instead has the suspect's license plate number, which is much more useful.
Mike, to the husband: Can I hug her?
4x17, Mayhem, has a scene where Mike Logan and Lennie Briscoe run from their current crime scene to the basement, following a woman's screams. In the basement laundry room they meet the very high Omar Cabases, who is brandishing an indeterminate object at them.
Lennie: What the hell is that?
Mike: Put the burrito down, seņor.
Omar: You, you, you dying!
Mike: Only if I eat that thing.
The arraignment sequence in this episode is something that must be seen to be believed as it stacks multiple defendants in sequence, with the judge's reactions and two of them staging their own hijinks.
From Season 10, Episode 9 "Sundown":
Dr. Elizabeth Rodgers: Right now, I've got to get a javelin out of somebody's chest.
Lennie Briscoe: What made you go into this line of work?
Dr. Elizabeth Rodgers: Free javelins.
From Season 20, episode 4, "Reality Bites":
Connie Rubirosa: What?
Mike Cutter: Having fun?
Connie Rubirosa: I am going to kill you, and then, I'm gonna kill McCoy.
Mike Cutter: On camera?
Connie Rubirosa: I don't care, I'd be better off in prison!