The most common way to complete the phrase “What’s up” is with the word “doc” to create the informal greeting “What’s up, doc?” This phrase gained popularity from the movie “Casablanca” (1942) and is still used today, often playfully.
However, depending on the context, you could also complete the phrase with:
- Friend’s name: “What’s up, Alex?” (more casual)
- “Sir” or “Ma’am” (more formal)
- Nothing: “What’s up nothing, much?” (informal response)
- A descriptive phrase: “What’s up with the rain today?” (asking about something specific)
Ultimately, the best way to complete the phrase depends on the situation and your desired level of formality.