I was wondering the same thing, there aren't too many possibilities. The chances of a male on female hormones lacitating are pretty much nil but maybe they can reproduce the hormone which begins milk production in a pregnant female? I'm sure there are cases of it happening but it has to be a very very rare occurance in real life. I doubt it though, too many possible side effects, the other possbility is using a syringe to inject the liquid and then filming it being squeezed out. Sounds painful but many of us like pain especially on the nipples. I've personally using a burning cigarette on mine, not long enough to cause any burns or scarring, just enough to get the intense heat. Your best bet is to google the topic and you might get lucky and hear from one of the actresses or film crew. Please post your results.