Mooning is the act of displaying one's bare buttocks by removing clothing, e.g., by lowering the backside of one's trousers and underpants, usually bending over, whether also exposing the genitals or not. Mooning is used mostly in the English-speaking world to express protest, scorn, disrespect, or provocation but can also simply be done for shock value or fun. Mooning may be considered indecent exposure, depending on jurisdiction and context.

Moon has been a common shape-metaphor for the buttocks in English since 1743, and the verb to moon has meant 'to expose to (moon)light' since 1601.^{[citation needed]} As documented by McLaren, "'mooning', or exposing one's ass to shame an enemy [...] had a long pedigree in peasant culture" throughout the Middle Ages, and in many nations. Formerly, "mooning" was slang for "wandering idly" and "romantically pining."

In Chilean Spanish, the act of mooning is known as cara pálida, lit. "Paleface".

The legal position of mooning varies between jurisdictions, from indecent exposure to legal self-expression. Some example cases include:

Justin Drew Bieber ( /ˈbiːbər/ BEE-bər, born March 1, 1994) is a Canadian Pop/R&B singer-songwriter, musician, and actor. Bieber was discovered in 2008 by Scooter Braun, who came across Bieber's videos on YouTube and later became his manager. Braun arranged for him to meet with Usher in Atlanta, Georgia, and Bieber was soon signed to Raymond Braun Media Group (RBMG), a joint venture between Braun and Usher, and then to a recording contract with Island Records offered by L.A. Reid. Bieber's debut single, "One Time", was released in 2009 and peaked in the top twenty in Canada and charted in the top thirty in several international markets. His debut album, the seven-track EP My World, followed in November 2009, and was soon certified platinum in the United States. He became the first artist to have seven songs from a debut album chart on the Billboard Hot 100.