"Whatever for?" vs. "What for?"
From Watership Down, by Richard Adams:
Chervil: “It’ll have to be reported.”
Bigwig: “Whatever for?”
Chervil: “Because it’s unusual. Everything unusual has to be reported.”
I think saying “What for?” would work there as well, so is there an added meaning when using “Whatever for?” with whatever instead of just what there? Is this a colloquialism?
Solution 1:
Whatever for?, rather than just What for?, adds a greater sense of incomprehension on the part of the speaker over what has just been said.