Just for your reference:
1 我没有听错吧? Did I hear (that) right?
2 有没有搞错? Did I/you not make a mistake? / Are you sure? / Are you sure you are not making any mistake? etc
3 信你才怪!Well, I would/should be supprised if I bought your story.
4 我现在在外面(我想说我正在在外面,不在家里) I am not at home right now.
5 你居然... I never expected that you would... (Sometimes you can just let "the air" help you express “居然" in English. For example: 你居然还爱他?!YOU STILL LOVE HIM???!!! 她居然买了一辆新车?! She bought a NEW car???!!! Another way, probably not a popular way: 你居然如此待我!Oh my, that you should treat me so.)
6 你到底想干甚么? What are you trying to do, anyway?