What Should I Say ?

[lenanils]

what should I say when somebody ask me " What's Up?"

[Svejk]

the sky

[Henrietta]

Say the same back as it's a form of "hello" unless it's said aggressively in which case back off and find help.

[Henrietta]

Another interpretation when someone is saying "What's up" is they could be asking you hows things or maybe enquiring about your welfare.

[gness]

It depends on the situation, Lena.....if you look troubled they are asking you to tell them what is wrong....

Sometimes it's just a greeting and you can say....Hey, I'm fine...how are you?

Your English is coming on well....x

[Old_Geezer]

Depends on the context. Literally a good response is, "The opposite of down" :-)

Otherwise it could just be "small talk", a greeting. A suitable response might be, "Not a lot, what's up with you ?", spoken in a concerned rather than aggressive way that is.