Okay so in the Dictionary of Sexual Language and Imagery in Shakespearean and Stuart Literature, I found the following explanation for the meaning of Coin in merry ole times.
Coin - woman in her sexual capacity. Hence stamping or coining become coital figures..........Grose (1785) has; 'MONEY, a girl's private parts, commonly applied to little children, as, take care miss, or you will shew your money'; F&H: 'money-box,-maker, spinner....
*Qanon is right, these people are sick. I guess this gives coin purse a new meaning for me. I found other stuff. Can't wait to share/sarcasm*