Because their primary duties were childbirth, their breasts became saggy and red from the excessive sucking upon their ample breasts.
Basically Turkey Tits is the name for saggy and red nipples which resemble a turkey's wattle.
"Well, good luck to that guy if he's trying to get married. He's got severe acne, a club foot, and the biggest turkey tits I've seen in a long while."
Person B : Severe case of turkey tits. I wouldn't get used to it, they'll go away in a bit.