你在拽我的腿吗

1)Are you kidding=Are you pulling my leg?

你在开玩笑吗?

Example:

-Do you know that Andy is going out with someone?

-What? Are you kidding? I am still a bachelor.

-So who is that girl walking along the street with you yesterday?

-My god! She is my sister and she has got married and her baby is 5 years old!

-Wow, your sister looks so young.