Back-formation means the removal of (supposed) prefixes or suffixes of a word to form a new word. (See the Wikipedia references, below, for countless examples of these.) If the word in question was not actually formed using the prefix or suffix that is being removed by back-formation, then the result is a humorous non-word, which is the main subject of this page. In some cases, the back-formed word is then re-suffixed to form a new (typically more complicated) word.
Extra syllables: Our "Human Resources" representative spoke of a "fictitional" employee whom she used as an example to illustrate the new Benefit Plan. My guess is that this word was inappropriately back-formed from fictitious. (The back-formation is fictit, which would be a fictitious thing, and then re-suffixed to make fictitional, which is the quality or characteristic of a fictit.)
"Allegator", used in jest by Harry Shearer on Le Show is a bogus backformation from "allegation". (Here, to allegate is the back-formed verb which means to allege.)
Harry Shearer: Le Show
Wikipedia: Back-formation and List of English back-formations
A neologism (newly coined word) is often the result of a back-formation.