During the act of a man and a woman having sex, the man thrusts as hard as he can, twice in quick succession,the first in the vagina and the second into the anus, causing the woman to jump off from the surprise and pain.

To ejaculate on the receiver's face, getting cum in both eyes (by purpose or accident)

While going down on her, you get hit with a fart and a queef at the same time.

When you fuck up in a completely and easily avoidable manner

Taking two shots of fireball shooters at the same time