The derivation of the term "Goldbug" has its roots in the Republican National Convention, which was held in St. Louis on June 16, 1896, when William McKinley, then governor of Ohio, was nominated for President on the gold-standard platform.
On this momentous occasion, the followers of McKinley, known as McKinleyites, held a parade, in which they wore black pants and gold velvet coats. Because of the principle for which they stood, and the clothes that they wore, these paraders were called, "Goldbugs."
When McKinley High School adopted the colors of black and gold, recollections of the original McKinley Goldbugs germinated in the minds of those who remembered the days of the late President McKinley. Thus, McKinley High School became known as the home of the Goldbugs and that we, the students, are referred to as Goldbugs.