Ciri shook her head. "Chicken, yes, but I've never heard of a hamburger or whatever a microwave is," she laughed.
Due to her roommate and Geralt, and jumping through dimensions normally, Ciri was well aware that there would be words and concepts she would not initially fully grasp that others took for granted as common knowledge. It would be the same if they jumped into her homeworld and didn't know that elves and the like walked side by side with humans.
"I do appreciate the help," she continued to smile. There was something about him that made her feel at ease. Maybe it was that laidback, quietness that she came to find in most of her friends- other than Jaskier, obviously. "Hmm, a chicken sandwich?"