There are various ways to reply to "what's up?", depending on how you are doing and what you are doing. You can answer with what you are currently doing, or what's going on at the moment, or just say "not much" and return the question. Q: What's up? A: I am reading/listening to music/having lunch. Q: What's up? A: It's a holiday today, so I am relaxing. Q: What's up? A: Not much, what about you? Q: What's up? A: Things are alright, what's up with you?

Whats up in todays language can mean a few different things. 1. What are you doing 2. whats happening (loose term in regards to now in life) 3. Can also be a greeting of hello.

Yes, it's a pretty flexible term, *but* can be used to express concern; for example: 'What's up? Did Manchester United lose again?' ;) No *genuinely*, if someone looks distressed or worried. I never use it as a casual greeting, but I guess I'm an exception. Oh, to answer your question, you could then answer: 'Yeah, it's time they got (yet) another manager' or 'I've got a bad headache/stomach ache through trying to learn English.' ;-)

To keep the conversation going, you could tell them what you are doing e.g "Nothing much, just doing my homework"

"What's up" is a question which means, "What are you upto?" or "What are you doing?", so the ideal reply would be something you have been doing lately, for example, "I was just watching a movie", or "Just relaxing these days". I would admit this question is very frequently asked, and sometimes it's just a casual greeting to start a conversation. There are some funny definitions of the term on 'Urban Dictionary' here: http://www.urbandictionary.com/define.php?term=what%27s%20up