"....is this a dagger I see before me, the handle toward my hand?
and on the blade, and dudgeon, gouts of blood..which was not so before."
Macbeth ii, 1
The 'bollock' dagger, the forerunner of the Scottish dirk was often termed the dudgeon dagger for the hilt material which was usually fashioned out of boxwood (dudgeon) and in the 16th-17th centuries. By Victorian times, the blushing and prudish hypocrisy (P.C. even in those days
forced the anatomical reference above the belt from the male metaphor to the lobed kidneys, and it began being termed the 'kidney' dagger.
Nice example, and wanted to add some historical context pending the details on it.