The story
From contra- + fibular + -ity + -s. From a 1987 episode of the British television comedy Blackadder, after Dr. Samuel Johnson boasts about his newly completed dictionary containing every word in the English language. Blackadder wishes Dr. Johnson his "most enthusiastic contrafibularities", upsetting Johnson, who quickly adds the alleged word to his manuscript.
Etymology from Wiktionary, CC BY-SA 4.0.