(as) happy as a flea in a doghouse

What is the origin of the idiom "happy as a flea in a doghouse" and when to use it?

The origin of the phrase "happy as a flea in a doghouse" is not well-documented, and its precise origin remains uncertain. However, it is believed to have emerged as a playful and humorous expression, likely originating in English-speaking countries. The phrase is often used in a playful or sarcastic manner to comment on a person's ability to find joy in unexpected or confined circumstances. It can be used in a wide range of contexts, such as describing someone's satisfaction with a small and cozy living space, finding delight in a mundane task, or humorously highlighting someone's positive outlook on life.