London - Marilyn Monroe knew it and so did Jessica Rabbit - "stick your bottom out if you want men to find you irresistible".
Now scientists have found that it's instinctive to strike such a pose when an attractive male is near. In a study of sexual cues, female volunteers were photographed by a woman.
She then pretended to have camera trouble and called in a hunk to take over. The snaps were compared and showed the women pushed out their behinds for the man's photograph.
Researcher Zeynep Senveli said: "Women seem to arch their back when flirting."