The following piece is from a "missing" scene from the episode where Abby and McGee go to Mexico (third last episode of season 7).
"Now I can see why Ziva took the couch in Paris," Abby said, walking away from McGee.
"I thought Tony took the couch," McGee replied. Abby turned around, smiling a wide smile.
"Oh, Timmy! Oh my God, it's happened!"
"What has? Oh, no, no, no. They wouldn't do that. They couldn't do that."
"Alright then, you're an investigator, I'm a forensic specialist, let's get proof and come to a conclusion like we do with cases."
"OK, well, we know for a fact they did share a hotel room," McGee began.
"I rest my case," Abby replied.
"Hold on a sec, Abs, I'm thinking. Tony told me he took the couch after losing a coin flip."
"Well, Ziva told me she took the couch voluntarily because Tony would have had a sore back otherwise. Rule #7: Always be specific when you lie."
"This means they definitely did..." McGee almost choked on the words. "They shared a bed. But maybe that's it, we don't know for sure and we certainly can't ask them."
"You're right; they could have just kept that secret. If they had told people, they would have jumped to conclusions, and that's never good. But Paris is a romantic city, McGee."
"I'll give you that one. I'd kill to go there with y-" McGee stopped himself. Abby tried to ignore the awkwardness and continue with the discussion.
"And Tony and Ziva are kinda...you know."
"Oh, it sounds so cheesy when I say it, but they're soul mates."
"You really think so? Well, there has almost always been tension between them. And Ziva was really on the edge when Tony was on the Seahawk. Anytime anyone mentioned his name, she jumped about a foot in the air and all of a sudden had this desperate, weak look on her face. She practically followed Gibbs around all day hoping he would go into MTAC and make a call."
"And Tony, well, Tony saved her."
"Why does no one give me credit? I was there, too! I nearly get killed by terrorists too!"
"I know, honey, you're just...not like Tony. He was the one who faced Saleem so bravely. He was the one who nearly fell apart when he heard she was dead. He was so depressed."
"OK, look, can we just come to a conclusion already? I'm tired."
"Fine, I say they slept together in Paris. Bye."
"Where are you going?"
"To sleep on my lab table."
"Oh, come on, Abby."
"You forgot to use bottled water on your toothbrush. I don't wanna be anywhere near you."