When one of your buddies farts and it smells so terrible that in order to neutralize the horrific smell, you blow one of your own to thin out the smell of the original.
"Oh my god Freddie came over the other day and he totally farted in my face! I had to suicide fart just to ease the pain and dilute the shitty ass stench."
When someone you know is taking a dump in a public or private restroom, and while he is in mid-poo you open the door. Because of this, the person shitting is faced with the difficult decision of either hurrying up and pinching it off and then coming to kick your ass, or coming after you right then and there and risk poo falling out his ass and dropping on the bathroom floor.
The other night, Joey was taking a dump over my house and we gave him an open door dilemma. It was hilarious because he was mid-shit and came after us with his pants at his ankles and he just dropped the poopies all over the floor and stained it.