The act of defecating on the chest of a willing partner, be that male or female (equal opportunity grossness). What makes the frosty machine special from your tradition "dump on chest" is the consistency of the fecal matter. Traditionally, after eating a bunch of spicy food and washing it down with alcohol, the poo stream tends to get a mushy, "is it a solid or is it a liquid" consistency. When dropping this sort of brown trout on the breasteses, you are accomplishing a frosty machine. Also called a "custard machine".
My new girlfriend is a freak, she actually takes me out for Spicy Thai food, hoping I'll give her a frosty machine that night. I think I am going to ask her to marry me.