1 general:: Phrase(s): make a killing Fig. to have a great success, especially in making money. • John has got a job selling insurance. He’s not exactly making a killing. • Bill made a killing at the racetrack yesterday.
McGrawhill's American Idioms And Phrasal Verbs
2 general:: Enjoy a large and quick profit, as in They made a killing in real estate. This expression alludes to a hunter's success. [Slang; late 1800s]
American Heritage Idioms