Harry took the hint and sat down next to Percy, who was wearing brand-new, navy-blue dress robes and an expression of such smugness that Harry thought it ought to be fined. (Harry Potter 4 [US Version]: p.415)[Bold font is mine]
I thought at first ‘fine’ in this sentence meant ‘to make somebody pay money as an official punishment’. However, I’m starting to doubt my first judge; I couldn’t find any examples of the ‘fine’ which accepts blamable things, like smugness, as its direct object.
Would you give me the true meaning of the sentence?