what’SUP 要怎麼回覆？

Here are some possible responses:

1. Awesome. 非常棒！
2. Great! 很不錯呢！
3. Pretty good. 還好啊！
4. Not much happening. 沒什麼特別的。
5. Everything's okay. 就這樣而已。
6. Same as usual. 跟往常一樣。