I always loved the concept of having a flag that lets everyone know who is about to keel-haul them.
“Look, cap’n, it’s Bart Roberts!”
“Don’t be stupid, boy. Bart Roberts has the skull facing to the left and an hourglass. As you can see if you look closely, that skull is wearing a bandana. It’s Morgan.”
“Sorry, cap’n, but Morgan’s flag doesn’t have the skull over crossed swords. I do believe it’s Calico Jack.”
“Ah shit the flag’s gone red.”