...hold on a second.
So, the gang’s investigation of the cave they’re trapped in comes to a halt when they reach the
obvious fake wall mysterious treasure chest at the end.
Inside the chest, a skeleton head with a microphone inside asks for the password, and they try a lot of pirate-y phrases to no avail. They’re completely stumped.
However, Shaggy then says:
“How about ‘yum yum yum and a liverwurst à la mode!’”
…is revealed to be the secret password.
Now, the episode immediately hurries on from this scene, but two implications really deserve due time to sink in:
1. This band of hardened criminals, who have tried to kill the gang in multiple ways, decided to set “yum yum yum and a liverwurst à la mode” as their official password.
Every single time someone has to come or go, they have to say that. Out loud. In front of everyone.
2. If Shaggy had not randomly said that exact non-sequiter, in that exact way, at that exact time, the gang would have been trapped in the caves until were dealt with by the bad guys or died.
Why exactly do the police in the Scooby-Doo universe give these kids credit for solving mysteries, again?