A twenty sided die, or a system which has been used to base games off of. Also damages the Dungeon Master's walls after rolling low many consecutive times.
Player: Sonofabitch! Another 1?! How dare you betray me?!
*Throws d20 in a random direction as hard as he can*
Dungeon Master: Goddamnit Joe! That's the fourth time you've done that! I'm sure as fuck not paying if there's any damage!
Dm: roll arcana Leon: are you fucking kidding me
Jim: did it roll low again?
Leon: IT ROLLED A FUCKING 3 AGAIN
Emma: just get better a better d20 Leon: fuck you