There are 1 results of your search for plumber's crack.
plumber's crack
Cleft of buttocks exposed above an ill fitting pair of pants or trousers: I have to be careful when I sit down otherwise I'd show my plumber's crack.
Contributor's comments: Originally in the Penrith region of Sydney, I have only ever heard and used this expression, and never "councilman's cleavage" or any of the other variants.