When the gas from a woman's fart enters her vagina. The term is derived as follows: Fart UP pusSY. Not to be confused with a queef, which describes the expulsion of air from a woman's vagina.
If you are a girl, and you are wearing tight jeans, sitting in your car, and you have to fart...if you are sitting, you are already in a "few viable exits" situation; so sometimesthe bubble goes FORWARD, and slips up your pussy; voila! Fupsy!!
This is a wordexplaining the sex life of a farrett. It explains how they mate and what exactly they do while having sex. Believe it or not, this word is used quite often in everyday life.