What is the origin of phrase happy as a jailbird?

The phrase "happy as a jailbird" is actually not a common expression. While it's possible someone might use it humorously, it doesn't have a widespread usage or recognized origin like some other idioms.

It's likely that the phrase is a modern invention that plays on the common misconception that prisoners are content in their confinement. This is, of course, far from the reality of prison life, which is often marked by hardship, isolation, and deprivation.

If you're looking for a similar idiom that is more established, you might consider:

* Happy as a clam: This idiom describes someone who is content and at peace, often used to describe someone enjoying a peaceful and carefree experience.

* Happy as Larry: This idiom, originating in England, describes someone who is very happy and content.

While "happy as a jailbird" might be amusing, it's important to remember that the reality of prison life is far from joyous.