A：Get changed!
改变一下!
B：What for?
为什么?
注释：
What for?(为什么?)
= Why?
例：Why are you going to the post office?
= What are you going to the post office for?
= For what are you going to the post office?
(为什么你要去邮局?)
A: John, could you lend me twenty dollars?
(甲：约翰，你可以借我20元吗?)
B：What for/Why?
(乙：为什么?)