An Etymological Dictionary of the German Language/kacken
kacken, vb., ‘to cack, go to stool,’ early ModHG. only. Probably coined by schoolboys and students by affixing a G. termination to Lat.-Gr. caccare (κακκᾶν; allied to κακός?. Comp. MidHG. quât, ‘evil, bad, dirt’); the OTeut. words are scheißen and dial. drißen. In Slav. too there are terms similar in sound, Bohem. kakati, Pol. kakác. The primit. kinship of the G. word, however, with Gr., Lat., and Slav. is inconceivable, because the initial k in the latter would appear as h in Teut.