Urban Dictionary defines a hate crush as someone so irritating that they are constantly on your mind in the way that a crush would be. They might even turn up in the odd fantasy.
"Sarah Jessica Parker bugs me so much it's almost hot -- she might be my hate crush."
Yeah, I'm pretty sure I have a few of those. Not to the extent of the League of Evil Exes, they're just a few old friends who have changed over the years. I got a few people I love to hate. Just sayin'.