Pirate Flag
The pirate flag is an emblem used by the rabbibunnies rebelling against FunFrock as a sign of trustworthiness. Whoever wishes to show his good wills, must carry a pirate flag on his ship's mast. Without this flag, anyone who dares approaching the island is encountered by a fusillade from the rebels, eventually scaring him away. However, carrying this flag on a ship is highly approved by the rebels, who realize the good wills of the visitor.
If Twinsen attempts reaching Rebellion Island without a pirate flag on his catamaran, the rebels start shooting towards his ship, and Twinsen escapes to the Hamalayi Mountains. There, he meets another rebel, who tells him that he must retrieve a pirate flag if he wishes to reach Rebellion Island.
Following the rebel's advice, when robbing the Maritime Museum on Proxima Island, Twinsen steals a pirate flag, which he later hangs upon his catamaran. Once having the flag on, Twinsen is able to safely reach Rebellion Island, and join the rebels there.