The "10-minute rule" for Southwest Airlines refers to the time frame within which a passenger must cancel their flight to avoid a no-show fee or the forfeiture of travel funds. Specifically, you must cancel your flight at least 10 minutes before the original scheduled departure time. If you don't cancel within this timeframe, you may lose the value of your ticket. 

Here's a more detailed explanation:

• Cancellation Deadline:
  Southwest requires passengers to cancel their reservations at least 10 minutes before the scheduled departure time. 

• No-Show Policy:
  If you don't cancel within this timeframe and don't board the flight, it's considered a no-show. 

• Consequences of No-Show:
  A no-show can result in the forfeiture of your travel funds, meaning you won't be able to use the money you paid for the flight for future travel. 

• Flexibility:
  Southwest is known for its flexible cancellation policy, allowing changes and cancellations without penalty as long as they are made at least 10 minutes before the flight. 

How to Cancel:
You can typically cancel your flight online through the Southwest Airlines website or by contacting their customer service.