In a sexual situation. When one partner passes a fart from his or her butt to the target's vagina, then seals it up. Like a hot air Balloon, for which the southwestern US town's fiesta is famous.

The act of ejaculating in a woman's mouth. Then immediately creating a seal between her mouth and your anus. The next step is to fart thus inflating her cheeks like a balloon.

Blowing a raspberry on the vagina during 69

The action of expelling ones flatulence into a vaginal orifice

The hot air balloon is when you fart in someone’s mouth, they swallow said fart, and then due to the laws of physics that hot air rises, one must do a handstand in order for the fart that has been digested to make an expedited movement to the recipients colon. At this point it may be ejected forcefully onto or into the other partner, or into the room.

When a fart escapes into the vagina and then has to be refarted

While your mate is licking or tea-bagging the scrotum from behind or beneath and backwards, you fart in her or his face.

Extra points are awarded for a shot in the mouth (for it's logistical difficulty), or for one in the eyes, which results in pink eye.