bitch hook
n.— «Bitch hook. All-purpose quick-release hook for use with tractor and chain. Tha [sic] name comes from a hole in one end of the slot in the long, central part of the device. After the hook is dropped over the towing mechanism, a chain may be pulled through the hole, then allowed to slide down the slot until it catches. When it is pulled back up to the hole, it releases quickly.» —by Lewis J. Poteet in Québec Talking Country , 1992. (source: Double-Tongued Dictionary)