Silent But Deadly, a popular type of fart. Whilst in retrospect volume was never inversely proportional to the actual stench produced, it was generally accepted that the silent ones were the worst, as our elaborate pantomimes after inhalation would attest. Common remarks in the immediate aftermath almost always included, "He who smelt it, dealt it" (q.v.)
Steven Jackson developed quite a penchant for getting good lungfuls of the expelled air, and giving a considered and expert opinion on the quality. We always listened to his judgement.
(The reason this has popped up again seven years on is that the involved party has asked for his friend's name to be changed. We don't think anyone should be passed up for promotion based on their deep, fruity inhalation of other men's farts. But unfortunately we do not live in an ideal world.)

The reverse of the Silent But Deadly was the 'D.B.S' (Dangerous Bottom Syndrome), where the farter tried to make his guff more stealthy by tightly squeezing his bumcheeks together.
However, this often only resulted in a high pitched squeaker or the farter shitting their pants.