Fluid Dynamics
Summary: Greg finally draws a line at Grissom's request for samples, and that sends the rest of the team into the gutter.
A/N: Vague references to S5 episodes, no real spoilers. Thanks to Burked for serving as beta – any mistakes are all mine. My response to the Unbound Improv Challenge - first and last lines are provided, with 1,000 words to fill in the rest.
Rating: We'll go with a PG or so for implied sexual content.
Disclaimer: My voodoo doll malfunctioned, so Sumner Redstone hasn't signed over Viacom to me yet. Until I get a replacement, I still don't have any rights to CSI.

"You're kidding. Grissom?"

At the sound of Greg's plaintive wail, Sara paused in her examination of the section of circus tent in front of her. From the sounds of it, the young would-be-CSI was storming down the hallway with Grissom in pursuit. With an indifferent sigh, she went back to work.

"Greg, stop! Would I have the specimen jar if I were kidding?"

"Hopefully!"

"Do you want to do this in the bathroom or the locker room? Or you can use my office if you want to do it somewhere more private."

Sara's eyes snapped up, noting that Warrick and Catherine had also stopped examining their sections of the tent momentarily to listen into the conversation going on outside the room. They exchanged amused grins before resuming their tasks.

"No way! You're taking this haze-the-new-CSI kick of yours way too far," he said, his voice unmistakably shaky. "Grissom, I'm not giving you any of that to play with. Talk about gross."

Sara bit her lip, grinning as Warrick started to chuckle. Catherine's gloved fist pounded softly against the table.

"I'm not planning on playing with it, Greg," Grissom said impatiently. "The pattern on the suspect's mattress is all wrong."

"Then use some of that stale blood in your office."

"Blood has the wrong viscosity, Greg. A fact of which you should be well aware."

"The only fact I'm concerned with right now is that I'm not giving you a sample of that!"

Grissom's voice softened as he tried to coax Greg. "Come on. I'll even show you how we replicate the dispersion."

"Doesn't this count as harassment?"

"No, I'm pretty sure it doesn't," Grissom replied honestly.

"Look, I gave you a number one. I even gave you a number two. But there's no way I'm donating any of that bodily fluid. Ewwww."

Sara's eyes started to water as Catherine's soft snickering filled the room.

"Greg," Grissom's tone became even more cajoling, "there's no need to be embarrassed. You'll even feel better when it's over."

Warrick dropped the ALS.

"Then do it yourself!"

Unable to hold it in any longer, Sara started laughing quietly. It didn't last long.

"I don't like doing it to myself," Grissom stated.

Catherine set down her magnifying glass, pulling off her gloves as she wiped at her eyes. Warrick's attention stayed on the tent, but his cheeks were puffed out with repressed laughter.

"Well, don't look at me."

"Trust me, Greg, you would not be my first choice of who I'd turn to for assistance in that matter."

"Well, go get Sara to do it."

Hearing her name mentioned, Sara lifted her eyes slowly. She didn't know whether to kill Greg or her colleagues first. Catherine was doubled over, and Warrick had leaned back against the wall, his arms crossing over his chest as he watched her in open amusement.

"Fine. Where is she?"

Sara's jaw dropped. Warrick's arms fell limply to his sides, and he turned to stare at her incredulously. Catherine looked up, her eyebrows disappearing under her bangs. She tilted her head questioningly as she pointed to Sara, then towards Grissom's position in the hallway and back.

Unable to speak, Sara just swung her head from side to side slowly.

Walking into the Layout Room, Grissom froze when all three occupants turned to stare at him with their mouths open. "Sara, I need you to give me a hand."

Grissom's earlier confusion magnified when Catherine failed to contain her guffaw, collapsing into Warrick's arms as they both broke out in boisterous laughter.

"Sara, help me out here," Greg begged.

"You. Want. Me. To. Do. What?" Sara asked slowly and dangerously.

"Give me a hand," Grissom answered, looking around the room with a befuddled expression.

Cocking her head, Sara frowned. Grissom did have the aforementioned specimen jar in one hand, but the other also contained a long medical swab and another jar with what looked like a large piece of gauze in it.

"With what?"

"He wants a mucus sample. I am not your personal Booger Man," Greg said, quickly making his escape.

"Mucus?" Catherine and Warrick said in unison, falling into another bout of uncontrollable laughter.

"What did you think I wanted a sample of?"

Her companions reduced to tears, Sara answered by crossing her arms defiantly over her chest, raising an eyebrow knowingly. Grissom waved her out of the room quickly, his beard only partially covering the blush creeping up his body.

Once in his office, he closed the door, avoiding meeting Sara's gaze as he sank into his chair.

"Mucus?"

At her amused question, Grissom finally looked, glad to see the deadly glare was gone from her eyes. He gave a subdued nod.

"The gauze has been treated with a menthol compound. You insert it into the nasal passage through the nostril. Leave it in for a few minutes. The irritation causes a muciferous reaction. When you pull it out, you'll get a large amount of mucus."

Sara leaned back in her chair, scrunching her face in disgust.

"Would you rather I do it to you?" he asked with a twinkle in his eye. "It's very refreshing, actually. Completely clears the sinuses."

He sank back into his chair when the deadly glare returned.

"You really do like to torture Greg," she stated.

"It's not torture. The job requires an ability to work in a variety of very unpleasant circumstances. If a new employee can't handle the tasks I assign, then it's unlikely they'll be able to function in the field."

"Right. And you don't get any pleasure from it," she said doubtfully.

Grissom dropped his head as he moved around the table, the swab in hand. "You'll recall that I never asked you to do anything like this before," he pointed out with a friendly smile.

"That's 'cause you know where they'd be pulling that swab out of you if you tried," she shot back.

Grissom paused; he could actually think of several locations where she could have inserted the swab. None of them struck him as enjoyable. He smiled weakly.

"Sara, I do need a sample for this re-enactment."

"How much gelatin do we have in this place? We can make you some fake boogers."

Without waiting for his response, Sara headed down the hallway, gathering the necessary equipment to concoct their mock mucus. When she got back, Grissom had decided not to push the issue, and had cleared off part of his desk.

They quickly mixed up several batches, adjusting the water content until they got the desired consistency. Grissom took the vial of finished product and frowned. "Sara, go to the last row of shelves. On the bottom one, in the box, grab the amber jar," he instructed.

She handed him the container with a quizzical look. "Coloring. This is too clear. The results will show up better if we dye it a bright red," he said, dropping some of the contents into the vial.

"Uh, Grissom, that's not red," Sara noted, her eyebrows shooting up at the milky white fluid that resulted.

"I could have sworn that's where I left the dye," he muttered, his face the only thing turning a brilliant red. "We can't use this. We're going to have to make a new batch."

Grissom set the jar down, nearly knocking it over in his haste to get away from it.

Sara sighed. "Just don't get it all over your desk, or they'll wonder what's been going on in here."

The End