A/N: I've had this idea in my head for weeks now, ever since musings of NCIS and Katy Perry's song, "Waking Up In Vegas" collided and I immediately thought of Tony and Ziva. One-shot for now, but I might end up posting a follow-up chapter, if this is popular enough.

NOTE: I am aware this has already been done, but I promise I did not read any similar story. No plagiarizing is intended.

Disclaimer: I own neither NCIS nor the song that inspired this burst of craziness.

1

'Shut up and put your money where your mouth is
That's what you get for waking up in Vegas
Get up and shake the glitter off your clothes now
That's what you get for waking up in Vegas'
~Katy Perry, "Waking Up In Vegas"

Ziva David was not alone in bed. She knew this even though she had just woken up and had not yet opened her eyes. She could sense the presence of a sleeping body beside hers, feel warm breath tickling the back of her neck.

The question was—who?

She struggled to think back on blurred memories of the day before. On a special case in Las Vegas. Apprehending the suspect. Closing the case. Going out to celebrate. With her partner. With…

"Ziva?"

Tony.

She rolled over reluctantly. Anthony DiNozzo had apparently just awakened and was now watching her with confused eyes.

"Oh no…" she groaned, reaching a hand to her forehead in an attempt to calm her splitting headache. Hangover…

Tony sat up quite suddenly, revealing a bit too much of his naked body.

"Oh my God, did we…?"

"It appears so," Ziva mumbled as flashes of memory flew through her mind.

(stumbling into the room, passionate kissing, clothes flying everywhere, soft sheets, and a warm body pressed against hers)

"No…" he said in protest. "We didn't."

(he called her his angel, his precious angel, and she liked it, and cupids flitted across her consciousness because she was drunk and not really all there, but the alcohol smelled good on his breath)

A sudden horrible thought occurred to her. Angels. Like the ones on the ridiculously cheesy signs they'd seen advertising authentic Las Vegas weddings.

"We got married?"

Her partner pulled away, didn't seem to care that he was temporarily exposed as he pulled jeans over his boxers and a T-shirt over his muscular abdomen.

"I really hope not, Zee. That would be bad."

Understatement of the year.

"Shut your eyes," she commanded, cocooning herself in sheets. "I am getting dressed."

"Obviously I've seen you in the nude before-"

"I. Don't. Care. Eyes closed, now."

--

He shut his eyes and tried to remember last night, anything at all.

(stumbling down a crowded, bright, street, laughing, her soft, soft hands all over him)

"You can look."

He looked. Ziva had pulled on pants and a shirt. She was watching him and biting her lip.

"What happened last night, Tony?"

"We got drunk," he told her.

"I know that. What else?"

He avoided her eyes. "I…don't know. But we didn't get married, Ziva, my gut is telling me that much."

That was not an acceptable answer, and it infuriated Ziva that she honestly could not remember the details of the evening before. She looked down at her hands, clenched tightly on the back of a chair.

Tony was rambling. "Look, you don't have to believe me, but-"

"Tony…" Ziva said suddenly, holding up her hand. "…this is not my ring."

Tony's eyes widened and he went rigid. "No…it's mine."

"I see." The response was perfectly calm, measured, controlled. The next second, she was on top of him, pinning him roughly to the bed. "What does your gut tell you now, hm?"

"We didn't—get—married," Tony gasped.

"You have no proof! I have no proof!" Ziva shouted, climbing off her partner and yanking her hair behind her head with a rubber band. "Isn't there any way to find out?"

Tony sat up and massaged his chest. "Probably not. There are scores of fake Elvises conducting who-knows-how-many cheap weddings every night in Vegas…"

Ziva paced back and forth in front of the window. "Unbelievable. Completely unbelievable." She spun around and pointed accusingly. "This is all your fault!"

Hazel eyes widened in disbelief. "Me? Whose idea was it to go for a drink last night?"

"One drink! Not ten! You were the one that refused to leave until the key hours of the morning!"

"It's wee hours. And, if I recall correctly, you're the one who threw up in the potted plant in the hotel lobby!"

Her eyes widened. "Did that happen?"

He nodded sarcastically. "Um, yeah. Got us a few dirty looks, too, but I guess they're pretty used to it-"

"Tony!" Ziva crouched before him, grabbing his arms. "You remembered that. Which means maybe you can remember what else we did last night."

"Besides sex? Because I'm pretty sure we-ow!" He rubbed his cheek where Ziva had slapped it. "What was that for?"

"For seducing a drunken woman," she replied sweetly. "Focus. Try to remember."

Tony shut his eyes and Ziva watched eagerly.

"Uhmmmm…uhmmmm…"

Ziva jumped to her feet in frustration. "Tony! What are you doing?"

"Meditating. It clears the mind."

"This is serious, DiNozzo!" she yelled, throwing her arms into the air and resisting the urge to strangle the man below her.

He opened his eyes and stared up at her calmly. "I know that," he said. "And maybe if Abby was here, she could hypnotize me—or you—and we'd have better luck. But since it's just the two of us, I'm afraid you're going to have to be patient, sweet cheeks."

Ziva glanced at the clock on the nightstand. "There is no time for that! We have less than two hours to catch our plane back to D.C., and we must know before we face the others."

"Why?" he furrowed his brow. "We just tell them everything went well, we went to bed separately, and nothing else happened. You're a trained assassin. Can't you lie, Ziva?"

She tilted her head to the side and smiled slightly. "I can. You can't."

He stood and shrugged. "I get it. But what if we find out that we did indeed marry—and have to face the music? You said it yourself—I can't lie."

"You won't have to. I will lie, and you will snap your mouth."

"It's not snap, it's—never mind." He took a deep breath, pacing to the window and staring out. "Anyway, we didn't get married. I would know!"

"I think you put far too much faith in your gut, Tony," Ziva said, shaking her head.

"Never lets Gibbs down," Tony replied without turning.

"You are not Gibbs."

The gentle reminder made her partner turn.

"No. I'm not," he conceded. "Because Gibbs would never had made the stupid mistakes we made last night."

Ziva sat on the bed, putting her chin in her hands. "I feel like an idiot."

Tony sat next to her. "Me too."

"You look like one," she quipped, reaching a hand to his head. "Your hair is sticking up everywhere."

"Thanks, Zee-vah," he said jokingly, and she laughed.

They grinned at each other for another moment before the situation wormed its way in, and their smiles faded.

"We are still in a big predicament," Ziva said, glancing around at the messy room. "There has to be something here that will jog our memories."

"Well, we are federal investigators," Tony said professionally. He grinned and dropped to his knees on the floor. "Time to put that training to good use."

"This is not a crime scene," Ziva said, staring at her fellow agent's back as he looked under the bed.

Tony's reply was muffled. "It might as well be. We broke one of Gibbs' rules. Rule #12."

"Never date a coworker," Ziva recited, proud of her memory. "We did not date, Tony."

"Yeah, we pretty much skipped that part," Tony snorted, grunting as Ziva kicked him in the spine. He crawled backwards into view and glared. "Would you please stop doing that?"

"I do not understand how you can joke about this! It is infuriating."

"Y'know," Tony said slowly, rolling back onto his heels. "I think they give out certificates when people get married. Even in Vegas."

Ziva's eyes brightened and she leapt to her feet. "So if we do not find one, we are not married?"

"No, I think it'd be more accurate to say that if we do find one, we are married. If we were really that drunk, there's a chance we could have lost it en route to the hotel."

Ziva's shoulders slumped. "Great. So we will not know for sure."

He grinned and gave her the thumbs up. "Now you've got it. But, hey—if it really is lost, no one ever has to know. We can pretend it never happened."

"Except that, legally, I will be Ziva DiNozzo!"

"Some women keep their maiden name—don't you dare!" For she had advanced toward him with her hand raised to strike. He shrank away in surrender. "All I'm saying is, don't give up."

"I am not giving up," she protested, lowering herself to the ground beside him and gingerly lifting one of his shirts out of her way. "So we look for this certificate thing."

"It's our only lead," Tony confirmed. As he reached for a pile of things, his phone rang from the table across the room.

They both stared at it.

"Maybe they will go away…" Ziva whispered.

Tony, however, stood and moved forward. "Not if it's Gibbs."

Ziva caught him by the elbow. "Let me talk to him. Remember…I can lie." At his acquiescent nod, she rose and answered the cell, shutting her eyes briefly.

Please let him believe me.

"Agent DiNozzo's phone!" she answered brightly.

"Ziva, that you?"

"Of course, Gibbs, who did you expect?"

Her boss chuckled slightly. "Well…you are in Vegas. Tell me DiNozzo didn't get married to a pole-dancer."

Ziva struggled to keep her voice even. "I promise you…he did not get married to a pole-dancer."

Tony's eyes widened when he heard this. He gave her a meaningful look, and she mouthed, Keep looking! He nodded and turned away.

"Well, that's a relief. I'll expect you both back here tomorrow morning, reports on my desk."

"We will work on the plane," Ziva promised, watching Tony frantically search the dresser. "See you tomorrow."

"Tomorrow," Gibbs affirmed, and Ziva hung up, letting out a sigh of relief.

"He believe you?" Tony asked, glancing over his shoulder.

Ziva tossed the phone back onto the table. "I did not have to lie. I am not a pole-dancer."

"And we are probably not married, because I have not yet found any papers proving otherwise," Tony murmured.

Ziva began to help him search.

"It's like you said—married until proven single. Yes?"

"Whatever you say...Mrs. DiNozzo."

--

An hour later, they were short on time and there was still no certificate.

"I say we're finished," Ziva ruled, tucking a loose tendril of hair behind her ear. "We need to leave, and there is obviously nothing here to find."

Tony scratched his head, glancing around. Privately, he agreed with his partner, but his gut feeling was beginning to change direction.

"Fine. I'll start packing up."

"I need to go to the head. Be right back." Ziva disappeared into the bathroom. A moment later, there was a shriek.

Tony jumped to his feet, images of giant cockroaches springing to his mind. He ran to the door and knocked.

"Ziva?"

"Tony," Ziva said softly from inside the room. "There is something you need to see."

He opened the door and looked inside. Ziva was standing at the sink, her mouth set in a firm line. Her shaking finger directed his gaze to the toilet.

Caught between the seat and the lid was a sheet of white paper. Tony's mind was only able to think, How did that get there? before it registered the words visible on the protruding half:

'-arriage Contract.' And then…their names. Signed.

He slowly looked around and met Ziva's burning gaze.

"Shit."