What three actions does Shonagon offer as proof that Masahiro really is a laughing-stock?

Shonagon highlights Masahiro's tendency to engage in foolish behavior, such as his inappropriate laughter during serious moments, his clumsiness in social situations, and his inability to recognize when he is being mocked. These actions consistently undermine his credibility and reputation, leading others to view him as a laughing-stock. By showcasing these traits, Shonagon effectively illustrates how Masahiro's behavior invites ridicule and derision from those around him.