The best examples that come to mind are when ordering food. As examples:
• You speak English and Spanish and are ordering a burrito
• You speak Thai and English and are ordering Tom Yum
I imagine it could depend on numerous things:
• You primary language or ethnicity
• What sort of restaurant
• Who you’re dining with
• Who you’re ordering from
• and probably a lot more…
You use the one of the language you’re currently speaking, of course.