If you want a badass curse, just read the Bible. Killer bears, plagues, rivers of blood, mothers eating their babies -- the Bible doesn't mess around. Unless it's one of the following curses. Then it's totally messing around ...
4Stealing the Ark Means Hemorrhoids
After a particularly nasty spree of killing Israelites, the Philistines take the Ark of the Covenant to Ashdod. What happens next is like something straight out of a movie where people are cursed with hemorrhoids:
"The men that died not were smitten with the hemorrhoids; and the cry of the city went up to heaven. - Samuel 5:12
OK, that's not a type of movie that actually exists, but if it were, this is the disgusting Bible verse it would be based on.
3Jesus Gets Cranky When He's Hungry