Shelf-righteous

(adj.) Having or being characterized by an unprecedented lack of morality in the presence of others, often to please others. Someone who is shelf-righteous is congenitally virtuous, but often leaves their morals ‘on the shelf’ in the presence of their friends or coworkers. A shelf-righteous act is typically done to appease a peer whose view is highly bigoted or jaundiced.

Person 1:I can’t fathom why he would ever say such a thing. He’s not that kind of person.
Person 2: He probably said it in the heat of the moment, in the presence of his friends.
Person 1: Wow he’s so shelf-righteous.