The term used to describe someone's ass-crack showing above his pants, usually when bending down. Called plumber's crack due to the high amount of overweight plumbers in Australia who cannot get shorts to fit them. Example: Hehe, get a look at his plumber's crack. His stubbies are wayyy too small. (Stubbies are an Australian brand of shorts.)
PLUMBER'S CRACK
Meaning of PLUMBER'S CRACK in English
Slang English vocab. Английский сленговый словарь. 2012