Build a nice, cozy fire and seat the caldron on it.
Grab some supplies... Trunk of toad, nose of newt, eye of elephant... Maybe a little spicy schzwan sauce for zing and mint for a pleasant smell.
Toss the ingrediants into the cauldron, and add laundry detergent.
Simmer for fifteen minutes, stirring occacionally with a magic wand.
Dance around the fire waving a broomstick and chanting "Boil me a curse, boil me a curse!"
Remove mixture from the cauldron, take it downstairs, and splash a ladlefull onto the lintel of the downstairs neighbor's door.
Mwahahaha!! I curse you! I curse you to forever have to use coin laundries and pay to clean your clothes! Ha! See if you ever again do a load of laundry that consists of nothing more than a shirt, a pair of socks, and a pair of boxers with cute little penguins on them!
Walk away, laughing wickedly
(I sure hope I move before the next drought. 'Cause I really don't feel like paying for the downstair's neighbors' just-in-time laundering strategies.