I always find this scene awkward.
"Do not smoke in here...This is what happens" during autopsy examination...and holds up dismembered hand...Is he pointing to yellow fingers caused by smoking? does he mean death?
I always thought he said "do not smoke in here" to Brody (who was just about to light up a cigarette) I see nothing un-toward or 'off' with that line.
The "This is what happens" line, was (I think) due to a censorship edit (Hooper likely having more dialogue over the sequence depicting the remains of the chewed-up girl) which was likely shortened to maintain the PG rating?
I took it as an incomplete sentence along the lines of, "this is what happens when a large shark attacks a person."
He just wasn't able to complete the thought because of his increasing stress and agitation.
The screenplay has the "do not smoke" line buried in Hooper's description of injuries:
Left arm, head, shoulders, sternum and portions of ribcage intact.
(to Brody) Please don't smoke.
With minor post-mortem lacerations and abrasions. Bite marks indicate typical [this is what happens during] non-frenzy feeding pattern of large squali, possibly carchaninus lonimanus, or isurus glaucas. Gross tissue loss and post-mortem erosion of bite surfaces prevent detailed analysis ... Did you go out in a boat and look around?