They belong to the old guy in the internet Cafe. Unfortunately you cannot get his attention to return them. Get a green balloon from the Clown Store and take it to the boy in the Countryside. This will create a distraction.
You return them to the guy in the internet cafe.
The one with the tickets is the second of the two round cans to the right.
You can look around the island all you want. The "Underground Tunnel Tour" requires tickets. (see related question)
They are in one of the two trash cans near the Tour entrance (under the garbage).
They are in a round trashcan to the right of the Tour entrance. You'll have to sort though the garbage until you find them. (see related question)
Its by the jazz house, or the tunnel. Its in a trash can.
Once you have given a green balloon to the kid in the Countryside (not what you expected), the man at the Internet Cafe will talk to you. Return his tickets and he will give you one to use.
you have to find the t. in the trash but you have to go to the cafe and get him to look at you
You go to the city docks and enter it from there
in the tunnel. jump on the light cord to get a paper.
At the end of the tunnel.
the lady will ask you for tickets to go in the underground tunnel. go to the right and click on the trash can and move all the garbage. you will find the tickets at the bottom. go to the lady and give her the tickets. it turns out you have to return it to the owner.