used to put dice who weren't "performing" into a special bag, the "unreliable red brigade".... afetr a few months of exile they would be returned, to see if they were "up to snuff again" if not........ well, I own a blowtorch, 'nuff said !
In recent times; I found out that a dice will do "better" if rubbed quickly along the leg of the closest (playing) female in the group. Works wonders - of course, get the permission from said female first, she might.... "object", violently so =) Still, a feasible method - too bad I am forbidden to use while I GM....