Slate layers' nailbag 

Old saggy tits / labia, that are stretched to the extent of looking like a well-seasoned slate layers' leather nail bag.

"cor, she's got tits like a slate layers' nailbag"

Slate layers' nailbag by haliborange October 25, 2009

slate layers nail bag

A very saggy pair of woman's breasts.

Mate, she had tits like a slate layers nail bag.

slate layers nail bag by lennylightweight April 20, 2006