HUMMEL, HUMMEL!

I'm most of the way through Dennis Showalter's Tannenberg: Clash of Empires 1914, one of those military history books that are way too detailed unless you happen to have an endless appetite for details on the topic, as I do. Furthermore, I'm familiar with the campaign entirely from the Russian point of view (first in Solzhenitsyn's August 1914), so it's good to get the view from the other side of the front line. As I wrote jamessal, who gave me the book (thanks, Jim!), "he does a superb job of showing what it was like to be a front-line soldier at the start of the war and the many ways in which actual combat surprised men who had been well trained in peacetime; it reminds me of Keegan's magnificent The Face of Battle." But there is no perfection in this world, and on p. 284 Showalter irritated me with the following coy sentence: "Time and again the familiar Hamburg rallying cry, 'Hummel, Hummel,' and the equally familiar obscene response, served as password and countersign for men blinded by smoke and sweat." Fortunately, the internet came to my rescue; according to this page, the reply is "Mors, Mors!"—"an abbreviation of either 'klei di an'n mors!' (go scratch your a**e! or 'Klei mi an'n Mors' (Kiss my a**e! ) (there appears to be some dispute over the exact phrase)." Anybody know anything about this (presumably dialect) word Mors?