boob lip
When a girl wears a dress that pushes her boobs a little too far. Her boobs don't fit all the way in the dress and voila, the roll of excess boob that cascades over the top is called the boob lip.
Didja see that boob lip? Sure hope she doesn't bend over...might fall out.
plate-in-lip boobs
Also known as "National Geographic Boobs", plate-in-lip boobs are large, droopy breasts often with a dark ariola (sometimes referred to as the "titty circle"). Plate-in-lip boobs can be brought on by quick and overzealous weight gain, pregnancy or old age. A woman with plate-in-lip boobs normally desires the look of a more lofty sweater kitten and can acheive this with either duct tape and Ace bandages or extensive plastic surgery.
At 7 and a half months pregnant, I've developed a severe case of plate-in-lip boobs and would look more appropriate with a stick in my nose and metal rings extending my neck than in Gap Maternity clothes.