"tickled pink" の定義と意味

What is the origin of the idiom "tickled pink" and when to use it?

The phrase "tickled pink" is believed to have originated in the United States and gained popularity in the early 1900s. It has been in use since the early 20th century in casual conversations, storytelling, and informal writing, adding a lighthearted and playful tone to express the sheer delight or amusement one feels.