Buttock cleavage is minor exposure of the buttocks and the intergluteal cleft between them, often because of low-rise pants.
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.[1]
In the early 2000s, it became fashionable for young women and men to expose their buttocks this way, often while wearing low-rise jeans.[2] [3] The Cincinnati Enquirer called it the "new cleavage", and expressed views that "It's virtually impossible to find jeans to cover your hipbone".[4] In August 2001, The Sun celebrated a "bum cleavage week".[5]
Jeffreys (2005) identified British designer Alexander McQueen as the originator of buttock cleavage-revealing jeans, known as the "bumster".[6]
In 2013, Cosmopolitan said that ultra-short miniskirts and shorts exposing the lower buttocks had gained popularity among women, influenced by celebrities such as Lady Gaga.[7]
The terms plumber butt or plumber's crack (Canadian, Australian, and American English) and builder's bum (British English) refer to the exposure of the buttock cleavage. The expression "builder's bum" was first recorded in 1988. The terms are based on the popular impression that work in these professions frequently involves bending over in locations where bystanders are observing from the rear.[8] In the Netherlands the term Dutch; Flemish: bouwvakkersdecolleté and in Germany German: Maurerdekolleté and in Poland Polish: dekolt hydraulika is used, which can be translated as "builder's/mason's/plumber's cleavage". In France, it is usually referred to as French: le sourire du plombier, which literally translates to "the plumber's smile".[9]