I never actually wanted to lactate, and I've never been pregnant, but several years ago I suddenly began to (it ended up being a megarare side effect to a medication I was taking) and it was a startlingly wild turn on to my very vanilla significant other at the time! It was so weird to me that I was very glad when I eased off that med and the lactating stopped because it was uncontrollable and happened anytime something pressed against my boobs!