Wagging the dog—sometimes it’s real, sometimes it’s an expression.

Since dogs have been such a big part of our lives for thousands of years, it’s no surprise that they appear in expressions in many human languages.
In French, “between a dog and a wolf” signifies dusk or twilight. In Spanish, “like a dog in a canoe” means being very nervous and “little dog of all weddings” is a way to describe a highly social person.
In Italian, an admonition to stop beating around the bush is expressed as “stop leading the dog around the barnyard,” while the Russian expression for “like a fifth foot on a dog” refers to something useless.
In German, “a fat dog” is a startling piece of news and to say that people get on “like a dog and a monkey” in Japanese means that they are on bad terms.
Dog idioms show up in English, too, and I’ve always really liked the expression, “the tail wagging the dog.” It is used to describe either a situation in which a small part of something is controlling the whole of it or a reversal of the proper roles. Despite the actual meanings, it always makes me think of happy dogs who wag their tails so enthusiastically that their whole bodies, from the shoulders back, are involved in the action. It looks as though the tail is literally wagging the dog.
Do you have a favorite dog-related expression?