To perform spectacularly badly at an attempted task or activity, in a flourishing display of unprecedented misfortune.
Originates from the roleplaying
game, Dungeons & Dragons, where a die must be rolled to determine a players' level of success in performing certain tasks. Rolling a
one in such a situation would
almost certainly cause the task to fail catastrophically.
Person A: My chocolate fondue fountain just exploded somehow, and
ruined my entire
house.
Person B: Wow, did you just roll a
one, or what?