There are two in one of the round trash cans to the right of the Underground entrance. You have to dig through the trash.
(see related question)
On Counterfeit Island in Poptropica, the tour tickets can be found in the bank. Head to the bank and look for a ticket booth on the right side. You need to interact with the booth to receive the tour tickets that will allow you to join the counterfeit money tour.
In the bin near the tunnel entrance.
The tickets to the Underground Tour on Counterfeit Island are at the bottom of the round garbage can to the right of the entrance. Once you have them, you have to return them to their owner, who is at the Web Browser Cafe on main Street.
you get the ticket from a garbage can
Once you have returned the tickets to the man who lost them, use the one he gives you. (see related question)
On the right on the entrance to the tour, there is a garbage can. Dig through it all the way to the bottom, and there it is!
They are in the trash can by the tour guide.The trash can with the lid off
Go get the tickts out of the large trash can
you have to take the underground tour
You can look around the island all you want. The "Underground Tunnel Tour" requires tickets. (see related question)
go in the underground tour
dig in a trash can and there is a ticket. the character wont let you use it