Why does Serena not have a proper graduation cap on in the finale of season two Gossip Girl?

In the finale of season two of Gossip Girl, Serena van der Woodsen does not wear a proper graduation cap because she opts for a more stylish headpiece that reflects her unique fashion sense. This choice highlights her character's desire to stand out and break from traditional norms, aligning with the show's overall emphasis on individuality and personal expression. Additionally, it underscores her confidence as she embraces her identity beyond the conventional expectations of graduation.