Brimstone Beach Club Cards were held by members and allowed them access to the beach and use of its facilities.
Captain Blondebeard dropped his into a chicken while having a sneezing fit in his kitchen. It read:
"Brimstone Beach Club. Member Since 1632."
Guybrush Threepwood found it when he placed some maggots on a dead patrons chicken meal. They are the chicken away revealing the card.