Would there be other alternative expressions that can replace the phrase "what are you doing?"

Native speaker’s answer
Rebecca
Not necessarily! In this context, he's asking "what" the man is physically "doing". So it's hard to use other words to ask the question. You could ask, "what's happening?" or "what's going on?" but these are more about general situations, where the causes of an issue could be unknown. They aren't as specific as "what are you doing?" when you're asking about a specific action or behaviour. Ex: What's going on? You're making a mess everywhere! Ex: What's happening? The music is playing, but no one is dancing. Ex: What are you doing? That's not dancing.