Final answer:
A courteous server should respond to rudely-behaving guests professionally by remaining calm, addressing the situation politely, and offering solutions or involving a manager if necessary.
Step-by-step explanation:
When a courteous server encounters guests who insist on behaving rudely, the most professional response is to maintain composure and remain polite. A server should address the situation calmly and strive to understand the root of the guests' dissatisfaction, offering solutions where possible. It is crucial for servers to not take the behavior personally and to communicate effectively to ease the tension. For example, if a guest is upset about the wait time for their meal, a server might apologize for the inconvenience and assure the guest that their order is a priority. In situations where the rudeness escalates or becomes abusive, it is appropriate for the server to involve a manager who can further assist in resolving the issue.