Perhaps it would be easier if Natasha let herself think of this as being on a huge cruise ship. She's always been able to handle the sound of the engines on those. But, right now, she's using the word 'spaceship' in her head as much as she possibly can. The quicker it becomes natural to her, the better.

"Yes," Natasha agrees simply, tilting her head back up to look at him with serious eyes. The coded message might not be a sign of extreme suspicion to her, but that doesn't make his statement any less true. "I've found that trust is a luxury I can ill afford." That is less true now, ever since she became a part of the Avengers and had to give up most of her spying. But, trust still doesn't come easy for her.

"Message reads: 'Bit low on stamps, I'm afraid. Keep the bunnies on their toes for me'." There's a brief pause during which Natasha searches Rush's face for any sign of confusion or misunderstanding. "Repeat it back to me, please."