掰掰 is a loanword from English 'bye-bye', used primarily in Taiwan as a casual farewell interjection. It is typically said at the end of a phone call, in person when leaving, or in text messages. Like the English equivalent, it can be repeated (掰掰掰掰) for emphasis. Pronounced 'bāi' in the source data, though in natural speech it is often 'bāi bāi'.