A adjective used to call someone out on a dumb answer, or a sentence with no logic.
What are you saying?? You're such a chewk!
A fishlike creature than is known for having little to no eyesight. Many people compare this blindness to more of a hand-eye coordination problem. Tests show, that when placed in an environment with a ball and a net, The Yishai will miss severely. Many sports players will compare people to / blame "Yishai" when a bad call/play is made.
How did you miss that??? You're such a Yishai