You want to search the treasure of Pirate Jack.
Playing as Doug:
Walk to the right to enter the restaurant. Talk to the barman and ask for a drink. He’ll give you a SLIPPERY TREAT. Talk to the man sitting at the table and learn about the staring contest and his sandwich. Challenge him to do a staring contest and he’ll start staring at you.
Playing as Toby:
Walk to the bar area on the right and take the SANDWICH from the table. Kasey will be distracted and now also loose his TROPHY. Walk to the right to go outside and talk to the train driver. He’s hungry so give him the sandwich. Now he’s thirsty.
Playing as Doug:
Walk to the right to join Toby and the train driver. Give the Slippery Treat to the train driver and he’ll get drunk. While he’s not paying attention, pull the large bolt connecting the train and the wagons so the train will crash. Just in time to reach the boat to the island.
Pick up the PADDLE from the pier and use the trophy on the WATER to fill it up. Take a BANANA from the tree and walk to the right to find a monkey blocking the entrance. You can try to lure the monkey away with the banana but he won’t move. Use the paddle to spank him and he’ll leave. Watching him walk to the right, the door of the cave opens and closes again.
Playing as Toby:
Join Doug on the right and step to the right of the entrance to open the door.
Playing as Dough:
Walk into the cave and pour the water into the bathtub to make a large stick float to the top. Pick up the STICK and leave the cave again. Use the stick to pry the large boulder on top of the cave off and let it take Toby’s place. Then walk into the cave.
Playing as Toby:
Walk into the cave and open the door on the right to find the treasure. Use the chest to see what’s inside.
Game source: A copy of the game was found here on the internet.