Facetious means you're kidding around, silly, acting as if..., ironic, irreverent....not serious.
Facetious is an adjective. The adverbial form is facetiously.
The likely word is "facetious" (done in jest, frivolous).
The word "facetious" comes from the French word "facetieux," which in turn is derived from the Latin term "facetia," meaning "jest" or "witticism."
abstemious, facetious
facetious
It has all the vowels in the correct order throughout the word
humorous in a playful, mischievous, or facetious manner
* abstemious * facetious
Facetious
Both "facetious" and "unoriental" are words that use the prefix "un-" to create a negative meaning. "Facetious" means not meant to be taken seriously, while "unoriental" indicates a lack of oriental characteristics.
Among a few are arsenious (old), bacterious, facetious, majestious (old). By turning facetious into facetiously, you even have all six vowels in one word, in proper order.
Facetious or insidious