Rationalization is the process of constructing a logical justification for a decision that was originally arrived at through a different mental process. Exemple : attending an art class pretenting only going there "for art sake" while the actual goal is to stare at nude model.
This process can be in a range from an external defense against ridicule from others to create a block against internal feelings of guilt.
Fig leaf are stylized representation of a leaf from a fig tree (or vine) used especially to conceal the genetic organs depicted on sculptures of nudes :
A reference to "fig leaves" might suggest something that camouflages insufficiently.