Cast Iron Stomach noun phrase
If someone has a cast iron stomach, they have a strong stomach that can digest unusual food and even bad food without being ill.
Jimmy must have a cast-iron stomach, when he drank milk with lime juice and felt perfectly fine afterward.
You must have a cast-iron stomach if you eat this stuff.
To have a strong stomach against bad or unusual food
This idiom became widespread around the early 1900s since cast-iron is a type of metal that commonly used in creating cooking utensils. Pans that are made with cast-irons are tough and resilient hence, making the meaning of the idiom.
To quit; to give up, stop doing something because you know that you cannot succeed; admit defeat
The team is not going to throw in the towel just because they lost one game.