Season 3, Episode 3
Ned Flanders proudly opens his new store, the Leftorium, with stock specially catered for left-handed people. But he feels cursed when he soon goes out of business and is forced to close. Riddled with guilt (because he wished for it to happen), Homer takes pity on him and encourages everybody he knows to use the store, thus saving the shop from certain closure.
The final scenes are reminiscent of Its A Wonderful Life.
See here for more details.
Notes & Screenshots: Lord Heath