Leap Up and Down (Wave Your Knickers in the Air)

"Leap Up and Down (Wave Your Knickers in the Air)" is a British idiom, specifically common in northern England, used to express extreme joy, excitement, or enthusiastic celebration. The phrase paints a vivid and somewhat absurd picture of uninhibited merriment. While the act described is unlikely to be performed literally, it conveys a sense of wild abandon and unbridled happiness.

The origin of the phrase is uncertain, but its imagery suggests a working-class or folk tradition where such behaviour might have been more acceptable or humorous within a specific social context. The inclusion of "knickers," a dated term for underwear (specifically women's underwear), adds to the phrase's playful and slightly irreverent tone.

The phrase is often used humorously or ironically, particularly when the situation being described is not truly worthy of such an over-the-top reaction. It can also be used to express genuine delight at positive news or a favorable outcome. The impact of the expression relies heavily on the context and delivery, and its usage outside of the UK might require explanation for full comprehension. It should also be noted that the use of "knickers" could be considered mildly offensive by some, depending on the social context.