"I can't use these dice; they're random!"
I have a set of metal dice that are my "Evil GM Dice" (tm). I often find they roll too well for me when I'm trying not to completely maim the PCs. Too many inopportune crits...a few player knights from our current Pendragon campaign have met grisly fates due to my Evil GM Dice crits.
Davy Jones
"Frightened? My dear, you are looking at a man who has laughed in the face of death, sneered at doom, and chuckled at catastrophe! I was petrified."
-- The Wizard of Oz