Dimac is a fictional martial art in the books of Robert Rankin, with practitioners poppiing up all over Brentford (and other places, too). The legendary Count Dante is, however, somehow the teacher of every one of these individuals.
Count Dante learned his skills in Tibet, and then broke his Dimac vow of silence by publishing various training manuals. Of these, volume 1 deals with attack, volume 2 with defence, and volume 3 with matters altogether unmentioned. Archroy, a practitioner of Dimac goes to New York to challenge Dante at the end of 'The Antipope', but is forced to withdraw this challenge when he finds out that his master is 80 and arthritic.
The Dimac code of honour requires that before any of its students engage any non-practitioner in combat, they give the a fair and reasonable warning that they are exponents of Dimac, the deadliest form of martial art known to mankind, and that they can instantly disable their foe, should they so wish, their hands and feet being deadly weapons, and that they can kill, maim, mutilate, disfigure, tear, rend and cripple their foe.
The nice thing about those who learn dimac is that they are very good at following traditions (or old charters, or something), and so repeat this warning almost verbatim, at quite regular intervals.