what does "jinxed" mean?
if someone says " you jinxed me and i got so much work" not in a serious way but as if he is kidding then what does it mean? and how to answer that.

Question

Answer

When someone says "you jinxed me"
It means you said something and made it so it might happen...
Example;
You: I can't believe we got locked out of the house.
Friend: Atleast its not raining
*it begins to rain*
You: Ugh, you jinxed it!

Answer

Like Luxyca said , you jinxed it means that you made something that people don't want them to happen happen.  Most of the time, they are bad stuff. 
I think he was kidding.  Like AT LEAST IT'S NOT RAINING, then IT started to rain, then if he said you jinxed it . IT means that now it is .