A topic that comes up in sociolinguistics is code switching in which bilingual communities switch between languages. A famous example in the U.S. is Spanglish, as seen in the movie Selena (where it ends up being a potential P.R. problem for the singer in BOTH the U.S. and Mexico).
Unfortunately, code switching is usually perceived up as being sloppy language, heavily frowned upon by monolinguals from all languages. Finding samples of authentic code switching (vs an inaccurate parody) can be tricky.
It turns the true king (raja) of code switching is probably India where code switching is completely acceptable because, as one woman explains “Hindi is a very friendly language.” You can find code switching in almost any modern mode or TV show from India, including the Indian version of Who Wants to be A Millionaire (i.e. Kaun Banega Crorepati/KBC). I bet that even if you don’t know a single word of Hindi you’ll understand this KBC clip.