only one i know of is the nightclub
forgot to mention you will need to get a quest item from the doctor in order to milk them.
Meet kirby in Downtown/Street area, she will invite you to her barn you can milk her and fill up the tank (harvesting the tank at 100% will reward you with the milky coin) , you can also milk anna and katherine.
If you mean the one you get from Tasha, go to the park restroom
