The idiom "so and so" is used to refer to a person or thing without using their name directly. It is typically used as a placeholder until the specific name is known or in cases where it is deemed inappropriate or disrespectful to use their name.

The idiom "a little of what you fancy does you good" means that it's okay to indulge in something that you enjoy occasionally. It suggests that doing so can have a positive impact on your overall well-being.

The idiom "all the rage" means that something is very popular, fashionable, or exciting at the moment. It describes a trend, craze, or sensation that is currently gaining widespread attention and acceptance.

The idiom "all and sundry" is an adjective that refers to a large number or variety of things, usually in a general or unspecified manner. It is often used to describe a collection of items or people, rather than individual items or people.

The idiom "before one can say Jack Robinson" is used to describe something that happens so quickly or unexpectedly that someone cannot react or respond before it has already happened.