Ok, this is what the cop was about to refer to from the last panel, when the driver says that he needs to keep the car cold as a result of "being weak against the heat".
ふしぜんな にく じゅばん を ぬいだら どーだ?
fushizen-na - fake looking
niku - meat / skin
juban - undershirt / singlet
wo - verb marker
nuidara - conditional form of "take off"
dou - how about
da - past form of "desu"
fake looking . skin . shirt . if take off . how about . is
How about if you take off that fake-looking skin.
There are all kinds of grammar points here in this one sentence, such as the "-dara" conditional, and the "-na" adjective that I'm not qualified to talk about. But, I especially like the "niku juban", or skin undershirt. This could also be viewed as "skin tunic". The thing the cop is talking about becomes clear on the next page. But right here, trying to translate this sentence without knowing what's going on is very difficult. For me, translating manga is a matter of moving back and forth through the story to see how a sentence on one page relates to the rest of the story later on, then coming back to figure out exactly what is being said at that point. That is, I don't view translation as a cut-and-dried process of analyzing one sentence at a time independent of the rest of the dialog.
I decided to settle on "How about removing your fake-looking skin?" as sounding a little more natural.
na - a stuttered part of "nani"
nani - what
no - of
koto - thing
da - past tense of "desu"
ka - question marker
wh- . what's . thing . is?
Wh-, what do you mean?
This is probably one of the best examples in this story of how Japanese works in terms of vagueness. "Take off your fake-looking skin" - "what skin?" becomes "what thing is?" A literal translation makes no sense, so we have to pull the meaning out from the context and add it to the English version.
However, "nan no koto da ka?" is very natural Japanese, and the nearest equivalent natural-sounding English is "Wh, what are you talking about?" So, that's what I used.
To be continued.