If you have Little Wooden Cubes from The Pestilence, you can choose which effect to aim for, either Food, Coin, or Workers, or Not Pestilence. If you don't get the effect you aimed for, i.e. aim for Food and get Coin, or aim for Not Pestilence and get Pestilence it will re-roll once.

Assuming even weighting of all effects:
Aiming for a specific effect has a 43.75% chance of success, but has an 18.75% chance of Pestilence.
Aiming for Not Pestilence has a 93.75% chance of success, but has an even 31.25% chance for each of the other 3 effects.