This is one of those sentences every word and every part of which makes sense but not the whole sentence.
From the movie Goodfellas:
In prison, dinner was always a big thing. We had a pasta course, and then we had a meat or a fish. Paulie did the prep work. He was doing a year for contempt, and had this wonderful system for doing the garlic. He used a razor, and he used to slice it so thin... that it used to liquefy in the pan with just a little oil. It was a very good system. Vinnie was in charge of the tomato sauce. I felt he used too many onions, but it was still a very good sauce. Johnny Dio did the meat. We had no broiler, so Johnny did everything in pans. It used to smell up the joint something awful... and the hacks used to die, but he still cooked a great steak.
It is very clear "hack" in this movie means a person that does regular boring things, who doesn't know how to game the system and be a "wise guy". But what does this sentence mean? Why "the hacks used to die"? Of the smell?