Like a dog with two tails

Origin

The universally understood image of a dog joyfully wagging its tail serves as the foundation for this phrase. The idiom amplifies this natural display of canine delight by humorously adding a second tail, suggesting an overflow of happiness so immense that one tail simply isn't enough to express it. While its exact genesis remains elusive, it likely arose from folk speech in the early 20th century, a vivid and charming hyperbole that effectively conveys an individual's boundless elation through a familiar and beloved animal analogy.