Are you playing with me? I am not sure it is the right translation, so I google it and this translation is 100% correct: "Are you playing trick on me". Hope it will help you!

你在耍我嗎? Are you messing with me? Are you f***ing with me? Are you playin' with me? (emotionally speaking, not physically) etc.

it means:Are u kidding me?

这些都是一些口头语或者流行语。学习汉语建议从学习规范的语言开始，等到基本的汉语框架固定了，再学习这些更“地道”贴切的汉语口语。

你在耍我吗? Are you playing with me? Detail: 耍(I think it is just a oral and informal word. Maybe it is from the TV serial or movies from Hong Kong, I am quite sure.) It implies that someone cheats you or even uses you if it is serious, or someone is just kidding you if it is not serious. Whether it is serious or not depends on the case.