Usage patterns
軽薄な態度a frivolous, flippant attitude
He adopted a flippant attitude toward his boss.
軽薄な言動frivolous, insincere words and actions
The people around him were disgusted by his frivolous words and actions.
軽薄に振る舞うto behave in a flippant, insincere manner
He often behaves flippantly even with people he's just met.