From the Super Mario Wiki
“You want somethin', chump? This is the fortress of the Robbo Thieves. You lost?”
Ishnail is a snail-like creature who is the leader of the Robbo Gang and the rival of Don Pianta in Paper Mario: The Thousand-Year Door. His name is a play on the main character of Moby-Dick, Ishmael, and "snail". He is the second Paper Mario character whose name is a reference to Ishmael, the first being Fishmael from Paper Mario.
Ishnail's base of operations can be found on the east side of Rogueport. Under his influence, the East side is far less secure than the West. It is unkempt, dirty, and serves as a hiding place for many bandits. His guard Gus even demands money for entering the further part of the east side. The west side is, on the contrary, rather secure and clean.
For 64 coins (a reference to the Nintendo 64), Ishnail informs Mario that he needs to buy a Dried Shroom, followed by a Dizzy Dial, in Peeka's shop, a secret sign known only to friends of Don Pianta. He then tells you to answer "Yellow" when asked what your favorite color is. It is possible to avoid paying Ishnail if you know these instructions.
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