Also known as silent but deadly. A fart that can not be heard but can sure as hell be smelt. This type of flatulent sneaks up on you and unless there is a breeze, hard to tell who it came from. Don't ever recognize this type of fart out loud otherwise you fall into the rule of: "Whoever smelt it delt it"
A special case of ninja-ass-gas - stealthy if you will - in which the gynacologist/unlucky bastard giving a woman an "inspection" gets farted on while up close and personal.
1) While getting a routine checkup.. Danae handed out free air biscuts to poor Dr.Rumple.
2) The Docter ran out of the room shouting.. FUCKINGAIR BISCUT!! I THINK SHE SHIT IN MY EYE