Spine Tit
A 'Spine Tit' is the slang definition used when people (usually men) are exaggerating about the small size of a females breasts. They are saying basically that a girls breasts are so small that they invert and protrude out of her back. This is impossible unless a person has a medical growth, mutation or some type of illness (elephantiasis etc.).
'Matt, i was touching up Samantha in science the other day, and i swear when i put my hand up her top, she has nothing there'
'Yea, i told you before you went out with her Ben, there is no point going up there, she had spine tits'
'Yea, i told you before you went out with her Ben, there is no point going up there, she had spine tits'