Sandy's a Code-Switcher.

Don't get excited. It's not as sexy as it sounds.

Code-switching - Wikipedia, the free encyclopedia:

"Code-switching is a term in linguistics referring to alternation between two or more languages, dialects, or language registers in a single conversation, stretch of discourse, or utterance between people who have more than one language in common."

Also describes the tendency to adopt the local dialect, and having lived with her in Hawaii, NC, DC and Japan, I'll attest she does that with relish.