Dirty Twenty
In Dungeons and Dragons, a roll that adds to 20 only after adding your modifier. Used to differentiate from a nat 20, as that roll means automatic success, where as a Dirty Twenty may not.
DM: Roll for initiative.
Rogue: Dirty Twenty.
Bard: Nat 20!
DM: Okay, so bard goes first.
Rogue: Dirty Twenty.
Bard: Nat 20!
DM: Okay, so bard goes first.