Real name: Dodecahedron
Nickname: Why would it have one?
Uses: Random Hour Generator. d12 System Core. Axe and two-handed sword damage. In many systems, the highest skill rank. Pokéthulhu. Thousand Suns.
Beloved because: Geeks overrate things others underrate, ergo, the geekiest of the geeks like the d12. The only dice left you can spin an open license around.
Hated because: Politics. Not a Hit Die. Gets lower numbers than 2d6. Too easy to roll.
Bonus niche tattoo: