An Etymological Dictionary of the German Language/Annotated/Duckmäuser

Duckmäuser, ‘sly, stealthy person,’ appears in Middle High German as tockelmûser, ‘sneak, hypocrite’; the Modern High German form is based anew on ducken, Middle High German tucken. A parallel form Tückmäuser is based on Tücke, ‘malice,’ the second part of the compound being connected with Middle High German mûsen, properly ‘to catch mice,’ then (with thievish intent), ‘to sneak.’