How does Guccio help Giovanni and Biagio play their prank?

Guccio helps Giovanni and Biagio execute their prank by providing them with the necessary tools and guidance. He offers insights on timing and execution to ensure their plan goes off smoothly. His support not only boosts their confidence but also enhances the effectiveness of their prank, making it more entertaining for everyone involved. Ultimately, Guccio's involvement is crucial in bringing their mischievous idea to life.