What is the origin of the idiom "happy as Larry" and when to use it?

The exact origin of the phrase "happy as Larry" remains uncertain, and there are various theories and speculations surrounding its etymology. It is commonly used in English-speaking countries, and while it has been in use since the late 19th century, the true origin has not been definitively determined.It is often used in casual discussions among friends, family, or peers to convey a sense of extreme happiness. Additionally, this idiom can be employed in a playful or exaggerated manner to express a lighthearted sense of well-being or contentment.