Greg (after finding semen on the doorknob): Trophy condoms.
Sara: Trophy condoms?
Greg: When a stud scores, he hangs his condom on his neighbor's doorknob.

Greg (grumbling about Grissom): You know, I hate it when he does that. I like to make a presentation, you know?
Nick: So, present.
Greg: Eh, forget it.

Greg (to Mia): So would you like to grab a bite later? I know a diner down the street that serves a mean liver and onions.
Mia: I don't eat out.
Greg: Never ever?
Mia: I don't like expectorant.
Greg: Really?
Mia: Kitchen staff talk while they prepare your food and then the wait staff repeats your order over the plate, and by the time you get your meal, there are several DNA samples coating it.
Greg: Wow.
Mia: Yeah. No, thank you. I don't eat birthday cake either.
Greg: Oh, blowing out the candles.
Mia: Ugh. Don't get me started.

Greg: '[about Kristy's shirt] Now, I've done this procedure on jeans and leather jackets but never on something like this. It's very see through. Very Jennifer Lopez.
Nick: Down boy.
Greg: It's going to be a tough one to prove. This is only step one. You see, when a person talks saliva naturally comes out of their mouth. Let's say that we're tossing the hog back and forth, right? [as he talks the camera makes note of the saliva that comes out of his mouth naturally in illustration of what he just said] What can you tell me about the hottie that goes inside this blouse, huh? Is it true she's a friend of yours?
Nick: What, is it on the internet?
Greg: Might as well be. Just remember that. My saliva is getting on you, your saliva is getting on me.
Nick: Gross. [Greg grabs a spray pump and sprays it on the paper] What's that stuff?
Greg: Starch and iodine. If this is saliva, we're going to get the old dalmatian effect. So, Nick, uh, if I wanted to meet this friend of yours...?
Nick: No.
Greg: Figured. [Greg sprays the paper] That's a pretty big spot. That's more than just a spray. In fact, looks like a distinct glob of spit.
Nick: Then Kristy was telling the truth. But it doesn't mean it was the security guard's spit.
Greg: Step three.
Nick: I'm going to need a sample.
Greg: Well, the guy knows he did it. He's not going to cough it up.
Nick: If you saw the girl that went with this blouse...you'd try.

Greg: [Greg limps into Grissom's office wearing only socks] What did you do to me?
Grissom: You had a reaction.
Greg: I'm Hazmat meat. Quarantine, here I come. [Greg pulls off the socks and puts both his feet up on Grissom's desk. Grissom examines Greg's right foot]
Grissom: Your right foot, I swabbed with a placebo, regular tap water.
Greg: Yeah, well, I'm not worried about the right foot.
Grissom: Left foot...eumycotic dermatitis.
Greg: Oh, great. It's probably fatal.
Grissom: It's a mildew-induced skin rash.
Greg: [stares at Grissom] You infected me with mildew?
Grissom: Here. Hydrocortisone. Follow the directions, clear it right up.

Greg: Brass subpoenaed Eiger's home phone calls in the last year.
Ecklie: Yeah, anything interesting?
Greg: Numerous calls from Eiger's house to Sy Magli's office.
Ecklie: Well, they were known business rivals.
Greg: Between midnight and 4 a.m., what I like to call: "Love Hours".
Grissom: Wouldn't be the first time that hate mutated into passion.
Greg: Public enemies, private lovers. So Jackie Collins.

Greg: Can I help it if I'm hip?

Greg: Cheese, milk, sweaters. What do these things have in common?
Catherine: Goat cheese, goat milk.
Nick: Goat sweaters?
Catherine: Angora.
Greg: Ding, ding, ding.

Greg: Everyone but the little guy was gettin' high and gettin' by. Daughter was on uppers, Mom's on downers and Grandma was on the cancer stick.
Catherine: Ritalin, Valium and Grandma's a liar.
Greg: Pants on fire.

Greg: FYI, 30 swabs in six hours is not realistic even for me.

Greg: Grissom, I have some information that'll be of a use to you but before you get it, I need a decision.
Grissom: What?
Greg: I'm tired of being on the fence here. Either I'm in the lab or I'm in the field. Which is it?
Grissom: Well, as soon as you can find and train a replacement, you can be in the field. Until then I need you in the lab. Now give.
Season 5

Greg: Grissom, I'd like to introduce you to Chandra Moore.
Chandra: Pleased to meet you sir, I'm a fan.
Grissom: Wow, you're hot.
Chandra: I'm... I'm sorry.
Grissom: You're eminating heat. This is a new infared camera. It's good for looking at evidence in the dark. (to Greg) Did you get her blood yet?
Chandra: My...why?
Grissom: So many reasons.
Catherine: (walking towards Grissom angry) Grissom? You can't possibly call that thing my office it's a cupboard.
Grissom: Catherine, I'd like you to meet Chandra Moore. She'll be doing DNA when Greg's in the field.
Catherine: Hello, I'm Catherine. (she turns right back to Grissom without giving Chandra a chance to introduce herself) We need to talk.
Grissom: Well, not now... too much work.

Greg: Hey Grissom, when you went to college did you live in the dorms?
Grissom: Surely, you jest.
Sara (laughs): You know they say a B.A. is worth a million dollars of extra income over your life.
Grissom: Yeah, but the present value of college tuition is about the same amount.
Greg: So you're saying college isn't worth the expense?
Grissom: I guess it depends on what you learn.

Greg: Hey! Yo, Cat!
Catherine: (she walks into DNA) I'm going to forget you called me that.
Greg: Sorry.

Greg: Hey, I hear you're cheating on me with an out-of-state DNA analyst.
Catherine: Apples and oranges, Greg. Fifteen-year-old hair samples no roots, room-temperature storage.
Greg: Room temp?
Catherine: Yeah, that's how we stored hair evidence back then. Microscopy was king.
Greg: Really? I thought Elvis was king.
Catherine: And you are how old?
Greg: Age is irrelevant in our relationship.
Catherine: Maybe so, but face it, Greg you just don't have the equipment.