Sentence:  One of his first, and most groundbreaking, stories was about "<WSD>cooping</WSD>," police slang for sleeping on duty. It was sparked when Burnham interviewed Jim Curran, then a New York City policeman, who referred to someone being "in the coop," Burnham recalled. ... Burnham heard that every day thousands upon thousands of New York police supposedly working the night shift were actually sleeping, stashed in coops all over the city, only to be awakened if a crime was discovered. ... <WSD>Cooping</WSD> was a natural result and a dramatic example of a city agency misusing its resources. 
Meaning of the word marked with <WSD> tags:  Of a police officer: to sleep or relax while on duty. (from 1960s.)