Is it spoken language
Sometimes, this spoken phrase is joined as one word "isit" or "izit.
Said to show interest in or surprise at what someone is saying.
A: John is gay. B: Is it? How do you know that?
A: John got his girlfriend pregnant, and they're getting married. B: Oh, is it! I don't even know he has a girlfriend.
A: Do you know that the youngest person who got pregnant in the world was just 5 years old! B: Is it?! Where do you read that?
This spoken phrase comes from South Africa.
If you fall for someone's trick the first time then they are at fault.
Are you going to mess with me again? Fool me once, shame on you; fool me twice, shame on me.