Hmm, looking further. It seems the linguistic phenomenon of code-switching is one accurate name for this, but there's also a sociological phenomenon of code-switching that is related but very different - intentional shifting based on social context or group that you're addressing.
Elsewhere in this same thread, someone was assuming the sociological cause for Spanglish, instead of the more organic linguistic cause that happens anywhere you have two cultures and languages in close contact. I suspect this blurred definition makes talking about this more complicated now, since sociological code-switching has become part of America's racialized sociology discussion.
If I had my druthers I'd split those two very different phenomena into separate terms, because they don't even produce the same kinds of linguistic patterns.
(Thanks for asking me to justify, my assumption was quite wrong regarding the scope of the term.)
> intentional shifting based on social context or group that you're addressing.
Isn't that register-switching?
It gets confusing in English, because the classier registers in English involves the use of more words of French, Latin or Greek origin, the less-classy registers rely more on anglo-saxon words.