You took out some milk. It was nice to drink and seemed harmless enough. Uncapping the gallon you start too pour the milk into the cup when you felt a bit odd and over poured the milk and accidentally spilled it over the floor as you tripped. Panicked you put the gallon back up and put it on the counter and go to get some paper towels to clean up the mess on the ground. You were thankful that the kitchen had a hard tile floor or moping up the milk would be too hard, but it seemed like more and more milk kept coming no matter how much you mopped. That's when you noticed something interesting. Your chest had grown about 2 sizes to an E-cup and were also lactating. You just hadn't noticed because your shirt was soaked in milk already. You were alone so you took off your shirt and tight bra and put your chest over the sink and examined your breasts. The once perky and pink breasts and nipples of yours now were swollen and brown. A few squeezes let milk out. You look to the goblet and see that it wasn't completely full like it had used to. You squeezed some more milk out and saw that the glass emptied a little bit more.
You thought to yourself "Huh... so that's what they meant by the cup being special... I wonder..." You then took the goblet and poured the remaining milk into the sink and your breasts shrank back to normal. You looked at the milky mess and decided to clean it up before trying anything else. Especially since you thought "They hadn't tried something like Soda... maybe other drinks have different effects... what to try next?"