Cassie-b

When Pigs Fly!

When pigs fly is an informal way to joke that you will never do something.

Example: “Do you think you will ever work at that company again?”
Reply: “When pigs fly!”

Pigs are heavy animals that stay close to the ground and do not fly, so when pigs fly is a time that will never come.

Another example: “Do you think your brother will be successful?”
Reply: “When pigs fly he will.”

When pigs fly is a time that will never come because pigs will never fly.

Yet another example: “Will you ever take her on a date?”
Reply: “Sure: When pigs fly!”