Cast Iron Stomach: be able to eat or drink anything without any problems
Example: He thought John must have a cast iron stomach when he saw him eating the spicy Korean food.
Catch 22: a situation where one thing must happen in order to cause another thing to happen that you cannot do until you have done the first thing
Example: Moving to other country without a work VISA or permanent job is a real catch 22. A Job application requires a work VISA, and a work permit application requires a permanent job.
Caught between two Stools (or fall between two stools): When someone finds it difficult to choose between two alternatives.
Example: He tries to be both good father and business man, but caught (falls) between two stools.
Close but no Cigar: when someone almost succeeded, but is not completely successful or correct, and get nothing
Example: It was very close but no cigar for Brown as he hit the ball correctly, but no hole in.
Costs an Arm and a Leg: a lot of money or extremely expensive
Example: I tried to find out the designer bag for my daughter's gift. It cost me an arm and a leg though!
Cry over Spilt Milk: not to be upset about something that has already happened and cannot be changed
Example: It's no use crying over spilled milk.
Cry Wolf: To raise an false alarm intentionally, to ask for assistance when you don't need it actually
Example: If you cry wolf too often, family and friends will stop believing you.
Curiosity killed the Cat: to warn someone not to ask too many questions about something
Example: What, courage man! what though care killed a cat, thou hast mettle enough in thee to kill care. (Shakespeare)
Cut Corners(verb): to do something in the easiest or cheapest way by skipping something important
Example: Can not be agreed to cut corners by building the bridge out of cheap steels instead of specification requirements.
Cut to the Chase: to get to the point without wasting time
Example: We didn't have enough time to talk so I cut to the chase and asked whether he was still refused.