Ahem... this is from Wikipedia, but amusing nonetheless...
"The term was coined by customizers in direct reference to Dagmar,[SUP][1][/SUP] an early 1950s television personality well known for her pronounced cleavage on Broadway Open House. Dagmar's physical attributes were further enhanced by low-cut gowns and the shape of her bra cups, which were somewhat conical. She was amused by the tribute."