During Saturnalia, an ancient Roman festival, slaves were permitted to speak openly to their masters, and give ... honest feedback while shielded from the immediate consequences. As the festival evolved over the centuries, there were stages where slaves were dressed by their masters in nice clothes, where slaves and masters ate the same food together at the same table (the masters' table, mind you!), and stages where roles were reversed for a day, which would be what we're seeing here.
