Idiom: an expression having a special meaning which is not clear from the usual meaning of the words in the expression
To have the world by the tail
Definition: to be happy and successful
EXAMPLE: Bill Gates (owner of Microsoft) now is the richest man in the world and he is running the largest company in the world.
He owns several sports teams and has a happy marriage. He certainly has the world by the tail.
EXAMPLE: Kevin just received a promotion and married the woman that he loves. He has the world by the tail.
For a song
Definition: to get something for very little money
EXAMPLE: I bought the car for a song.
EXAMPLE: They are getting rid of books at the store for a song because the store is going out of business.
To be sitting pretty
Definition: to be in a fortunate position
EXAMPLE: The family that won the lottery are sitting pretty.
EXAMPLE: Tom just inherited four million dollars. He is sitting pretty!
To paint the town red
Definition: to be out everywhere, being excited and rowdy (usually involving alcohol)
EXAMPLE: To celebrate our victory, we are going to paint the town red.
EXAMPLE: The morning after Terry painted the town red, he was feeling very ill.