Roll A One

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?

excrecement

When you pour quick-set cement into a public toilet, then poop on top and mix it in, congratulations you've made excrecement and been banned from Ikea

Ikea employee: Call the manager, someone's filled this display toilet up with excrecement again
Manager: Oh god not all the way to the top