english saying-a gut feeling

Meaning: If you have a gut feeling, you sense something about a person or a situation, without knowing why, but you're sure what you sense is true.

Origin: Probably derived from the fact that many people experience emotions and intuitive feelings as being centred on, or having a strong effect on, the stomach area, which is also called the gut. Interestingly, the nervous system's second biggest network of closely-interconnected neurones, after the brain, is located in this area of the body.