Yosh is a term used to express dissatisfaction after being easily deceived or duped.
Nate: Welcome to Cleveland Dave! Anything you want to do while you are here?
Dave: Well, a friend of mine said I should try a Cleveland Steamer
, so maybe we can go get those one day.
Nate: You want me to poop on your stomach?
Dave: What???? I thought it was some kind of dumpling. Aw man…totally got Yoshed.