facetious / factious / fictitious
Joking, given to faction, and made up.
Facetious means joking, often when the moment is serious. Factious means given to faction or split. Fictitious means invented. A facetious remark. A factious board. A fictitious name.
Examples
Use a facetious aside
Use a factious vote
Use a fictitious address
Avoid a factious aside (If you mean the aside was a joke.)