Buttock cleavage is minor exposure of the buttocks and the intergluteal cleft between them, often because of low-slung or loose trousers.

The crena is another formal term for the cleft between the buttocks, and the medical term is posterior rugae.

History

When faced with indecency issues back in the 1930s, W.G. Cassidy explained in an essay titled Private Parts: A Judicial View that exposure of a buttock cleavage may come under "other private parts" in Australian law, though indecency generally involves exposure of the genital area.

In the early 2000s it became fashionable for young women and men to expose their buttocks this way, often in tandem with low rise jeans.The Cincinnati Enquirer called it the "new cleavage", and expressed views that "It's virtually impossible to find jeans to cover your hipbone". In August 2001, The Sun celebrated a "bum cleavage week" claiming that "bums are the new tits". In reaction to this trend, Saturday Night Live aired a parody advertisement in their April 16, 2006 episode for a product called Neutrogena Coin Slot Cream, in which host Lindsay Lohan appeared.