In 1965, Mary Quant said "A woman is as young as her..."
Correct answer: Knees

BlueEyedAlien
Miniskirts showed knees. It was meant to flatter women who bought mini skirts by suggesting they looked young. Another marketing ploy.

Yana
What the heck does that mean ? Never heard a lot of comments about people's knees before. She's the bee's knees ? Hubba hubba !