It means that you really know it.
If it can be read the same backwards and forwards.
It reads the same forwards and backwards, like 65456.
Eve. I don't know if there are any others.
They hop forward, they can't hop backward
Well how about~ Miller & Rellim Oprah & Harpo Did you know Hannah stays the same whether it is spelt backwards or forwards && did you know that if you spell Hanna It Can't be spelled back words hahaha ! =] Think before you write.
This is not an idiom. It means exactly what it says in grammatically-correct fashion.
Knowing something "by heart" means you have it memorized and don't need to have any notes or reminders.
An idiom is a phrase that seems to make no sense unless you know the definition. This makes sense, so it is not an idiom. Something caught the gleam of light from a shiny object.
An idiom for a mountain is "Make a mountain out of a mole hill" this means to make something unimportant of simple to something very important and difficult.
It means to hear about something, often by rumor and often when you are not supposed to know about it, as if you heard it on the wind.
A palindrome is a word that reads backwards the same as it does forwards, e.g., noon, eye, did.
No, it is a simple question. This is not a slang for anything or an idiom for something else. This person wants to know where you're going to eat - maybe they want to know a good restaurant or maybe they just want to know more about you.