"This has its advantages," she replies, too annoyed to be embarrassed, once she's over the initial surprise. At least she doesn't need to cover herself, her skirt just falls right down once she's on her own two feet. She doesn't bother retrieving her underwear. Possibly as a statement, possibly just because she doesn't see the point at the moment.

"And to answer your question, it's generally customary to be invited beforehand, rather than by interrupting," she adds, straightening her shirt and jacket, then reaching up to fix her hair.